Driver's seat goes forward lopsided/crooked, and backward at a minimum. The up/down/recline button works fine.

use a meter and test the switch and motor

possible switch itself

bad switch.? loose wires> to same>/ or just physically jammed.

It could be , but to replace it without testing would not be a wise idea . These modules can set DTC'S - diagnostic trouble code's .Having a qualified repair shop check it would be your best bet .
It's called driver seat module .
DSM Diagnostic Trouble Code (DTC) Index
DSM Diagnostic Trouble Code (DTC) Index DTC Description Source Action B1342 ECU Is Faulted DSM INSTALL a new DSM. REFER to Section 419-10 . B1530 Memory Set Switch Circuit Short to Ground DSM Go To Pinpoint Test J . B1534 Memory 1 Switch Circuit Short to Ground DSM Go To Pinpoint Test J . B1538 Memory 2 Switch Circuit Short to Ground DSM Go To Pinpoint Test J . B1663 Seat Driver Front Up/Down Motor Stalled DSM If the motor does not operate, Go To Pinpoint Test H (Navigator) or Go To Pinpoint Test I (Expedition). If motor operates, Go To Pinpoint Test J . B1664 Seat Driver Rear Up/Down Motor Stalled DSM If the motor does not operate, Go To Pinpoint Test H (Navigator) or Go To Pinpoint Test I (Expedition). If motor operates, Go To Pinpoint Test J . B1665 Seat Driver Forward/Backward Motor Stalled DSM If the motor does not operate, Go To Pinpoint Test H (Navigator) or Go To Pinpoint Test I (Expedition). If motor operates, Go To Pinpoint Test J . B1666 Seat Recline Forward/Rearward Motor Stalled DSM If the motor does not operate, Go To Pinpoint Test H (Navigator). If motor operates, Go To Pinpoint Test J . B1667 Mirror Driver Up/Down Motor Stalled DSM REFER to Section 501-09 . B1668 Mirror Driver Right/Left Motor Stalled DSM REFER to Section 501-09 . B1669 Mirror Passenger Up/Down Motor Stalled DSM REFER to Section 501-09 . B1670 Mirror Passenger Right/Left Motor Stalled DSM REFER to Section 501-09 . B1676 Battery Voltage Out of Range DSM REFER to Section 414-00 . B1703 Seat Driver Recline Forward Switch Circuit Short to Battery DSM Go To Pinpoint Test H (Navigator). B1707 Seat Driver Recline Rearward Switch Circuit Short to Battery DSM Go To Pinpoint Test H (Navigator). B1711 Seat Driver Front Up Switch Circuit Short to Battery DSM Go To Pinpoint Test H (Navigator) or Go To Pinpoint Test I (Expedition). B1715 Seat Driver Front Down Switch Circuit Short to Battery DSM Go To Pinpoint Test H (Navigator) or Go To Pinpoint Test I (Expedition). B1719 Seat Driver Forward Switch Circuit Short to Battery DSM Go To Pinpoint Test H (Navigator) or Go To Pinpoint Test I (Expedition). B1723 Seat Driver Rearward Switch Circuit Short to Battery DSM Go To Pinpoint Test H (Navigator) or Go To Pinpoint Test I (Expedition). B1727 Seat Driver Rear Up Switch Circuit Short to Battery DSM Go To Pinpoint Test H (Navigator) or Go To Pinpoint Test I (Expedition). B1731 Seat Driver Rear Down Switch Circuit Short to Battery DSM Go To Pinpoint Test H (Navigator) or Go To Pinpoint Test I (Expedition). B1735 Mirror Driver Vertical Switch Circuit Short to Battery DSM REFER to Section 501-09 . B1739 Mirror Driver Horizontal Switch Circuit Short to Battery DSM REFER to Section 501-09 . B1743 Mirror Passenger Vertical Switch Circuit Short to Battery DSM REFER to Section 501-09 . B1747 Mirror Passenger Horizontal Switch Circuit Short to Battery DSM REFER to Section 501-09 . B1950 Seat Rear Up/Down Feedback Potentiometer Circuit Failure DSM Go To Pinpoint Test J . B1952 Seat Rear Up/Down Feedback Potentiometer Circuit Short to Battery DSM Go To Pinpoint Test J . B1954 Seat Front Up/Down Feedback Potentiometer Circuit Failure DSM Go To Pinpoint Test J . B1956 Seat Front Up/Down Feedback Potentiometer Circuit Short to Battery DSM Go To Pinpoint Test J . B1958 Seat Recline Fwd/Backward Feedback Potentiometer Circuit Failure DSM Go To Pinpoint Test J . B1961 Seat Recline Fwd/Backward Feedback Potentiometer Circuit Short to Ground DSM Go To Pinpoint Test J . B1962 Seat Horizontal Forward/Rearward Feedback Potentiometer Circuit Failure DSM Go To Pinpoint Test J . B1964 Seat Horizontal Forward/Rearward Feedback Potentiometer Circuit Short to Battery DSM Go To Pinpoint Test J . B1987 Pedal Forward / Rearward Motor Stalled DSM REFER to Section 206-00 . B1988 Pedal Position Forward Switch Circuit Short to Battery DSM REFER to Section 206-00 . B1989 Pedal Position Rearward Switch Circuit Short to Battery DSM REFER to Section 206-00 . B1990 Pedal Forward/Rearward Feedback Potentiometer Circuit Failure DSM REFER to Section 206-00 . B1991 Pedal Forward/Rearward Feedback Potentiometer Circuit Short to Battery DSM REFER to Section 206-00 . B2312 Mirror Passenger Horizontal Feedback Potentiometer Circuit Failure DSM REFER to Section 501-09 . B2314 Mirror Passenger Horizontal Feedback Potentiometer Short to Battery DSM REFER to Section 501-09 . B2316 Mirror Passenger Vertical Feedback Potentiometer Circuit Failure DSM REFER to Section 501-09 . B2318 Mirror Passenger Vertical Feedback Potentiometer Short to Battery DSM REFER to Section 501-09 . B2320 Mirror Driver Horizontal Feedback Potentiometer Circuit Failure DSM REFER to Section 501-09 . B2322 Mirror Driver Horizontal Feedback Potentiometer Short to Battery DSM REFER to Section 501-09 . B2324 Mirror Driver Vertical Feedback Potentiometer Circuit Failure DSM REFER to Section 501-09 . B2326 Mirror Driver Vertical Feedback Potentiometer Short to Battery DSM REFER to Section 501-09 . B2477 Module Configuration Failure DSM INSTALL a new DSM.

The only way to solve this issue is to extract the seat and inspect. The front and back movement is different from the other actions that the seat may be able to do...

Look for damaged, dirty and miss aligned track components.

which maxi fuse gets hot ? # fuse , plus amps The power seats uses a 30 amp circuit breaker ,not a fuse . The horn gets power from the same circuit breaker . . Sounds like something is drawing to much current. Do you know how to use a amp meter to test current flow . Disconnect componets till draw goes away ? How to use a wiring diagram to pin point areas in a circuit to test ?
Is there corrosion on the pins where the seat circuit breaker plugs into ? Reach under your seats an see if one of the seat motors is hot .
DeVille
The left and the right power seat system consist of the following components:
• The seat switches
• The seat relay modules
• The 4 reversible motors:
- The front vertical motor
- The rear vertical motor
- The horizontal motor
- The recline motor
These 4 motors operate independently of each other.
When the entire seat switch is pushed to the FORWARD position, the forward input of the of the seat relay is grounded.
The seat relay module supplies battery positive voltage (B+) with a ground to the horizontal motor, in response to this input. In order to drive the seat forward, the motor runs until the switch is released.
The BACK position works similar to the FORWARD position with the exception that the voltage polarity supplied by the seat relay module is reversed causing the motor to run in the opposite direction. This action drives the seat backward.
These recline switches operate similar but independently:

The seat relay module could be bad , If you don't know how to do automotive electrical circuit testing it mite be a good idea for you to take your vehicle to a qualified repair shop.
Could have diagnostic trouble codes stored as well .
DTC B0846 +5 Volt Reference Out of Range
DTC B0856 Battery 2 Out of Range
DTC B1656 EEPROM Write Error
DTC B1658 EEPROM Checksum Error
DTC B1982 Source/Battery Voltage High
DTC B1983 Source/Battery Voltage Low
DTC B2101 Recline Aft Switch Failed (Eldorado)
DTC B2101 Recline Aft Switch Failed (DeVille)
DTC B2102 Recline Forward Switch Failed (Eldorado)
DTC B2102 Recline Forward Switch Failed (DeVille)
DTC B2103 Rear Vertical Down Switch Failed (Eldorado)
DTC B2103 Rear Vertical Down Switch Failed (DeVille)
DTC B2104 Rear Vertical Up Switch Failed (Eldorado)
DTC B2104 Rear Vertical Up Switch Failed (DeVille)
DTC B2105 Horizontal Aft Switch Failed (Eldorado)
DTC B2105 Horizontal Aft Switch Failed (DeVille)
DTC B2106 Horizontal Forward Switch Failed (Eldorado)
DTC B2106 Horizontal Forward Switch Failed (DeVille)
DTC B2107 Front Vertical Down Switch Failed (Eldorado)
DTC B2107 Front Vertical Down Switch Failed (DeVille)
DTC B2108 Front Vertical Up Switch Failed (Eldorado)
DTC B2108 Front Vertical Up Switch Failed (DeVille)
DTC B2109 Lumbar Aft Switch Failed
DTC B2110 Lumbar Forward Switch Failed
DTC B2111 Lumbar Down Switch Failed
DTC B2112 Lumbar Up Switch Failed
DTC B2115 Recline Sensor Failed
DTC B2116 Rear Vertical Sensor Failed
DTC B2117 Horizontal Sensor Failed
DTC B2118 Front Vertical Sensor Failed
DTC B2119 Lumbar Forward/Aft Sensor Failed
DTC B2120 Lumbar Up/Down Sensor Failed
DTC 2130 Seat Motor Failure

The control switch has developed a problem (intermittent contact or just broke inside) Replace the switch. That should fix it.

You can move the drivers seat back by turning on the power, getting in the seat and position your feet firmly on the fron flor with your back firmly against he seatback, and then engage the switch pushing back - while pushing like hell with your feet. You can actually hear the seat drive shaft turning while the seat moves back. The principle should be the same for moving forward, but pressure would have to be aplide to the back of the seat.

it could be the electrical switch that controls the motor, that is if there are two switches to the seat button which controls the motor.

I'm assuming this is a power seat. If so, there are separate motors that control the various functions of the seat such as forward/backard, recline, lumbar support, etc. It could be that the motor or an electrical connection to the motor for the forward/backward motion is faulty. Normally all of the motors would be on the same power circuit, so if some of the functions are working then it is probably not a blown fuse.

Just one other personal observation, I have actually seen an instance where some loose pocket change had spilled under the seat and a quarter had become wedged in the track that the seat slides in and had jammed the tracks so tightly that the seat would not move.

One thing to note is whether or not you hear anything when you try to move the seat forward/backward. If you hear a click or a buzz when you press the button then that could mean that something is physically jamming the seat tracks. If you don't hear anything when you press the button, then that more than likely means a problem with the motor or the electrical connection to the motor.