Passenger door is hard to open and close, a lot of resistence

The window indexing feature is used to lower the driver and passenger power windows approximately 4 mm when the door is opened. This is necessary to allow the top edge of the window to clear the window weather-strip. This feature will also raise the window to the fully seated position once the door is closed.
Is just the driver door not working ?
Observe the operation of the driver window and front passenger window while opening and closing their respective doors. The windows should index DOWN and UP when the doors are opened and closed.
? If either window does not index UP or DOWN, refer to Window Index Feature Malfunction.

Window Index Feature Malfunction
Ignition ON, observe the scan tool Driver Door Ajar Sw and Door Ajar Switch parameters while opening and closing the driver and passenger doors, the parameter should change from Door Closed to Door Ajar.
? If the parameter does not change when opening and closing the doors, refer to Door Ajar Indicator Malfunction .
Ignition OFF, disconnect the harness connector at the appropriate window motor.
Ignition ON, with the door closed, test for greater than 10 volts between the signal circuit terminal 5 and ground.
? If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
With the door open, test for less than 1 volt between the signal circuit terminal 5 and ground.
? If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
If all circuits test normal, replace the window motor.

Your best bet mite be to take your vehicle to a qualified repair shop (GM dealer )

It should tell you which one .
Driver Door Ajar Malfunction
Passenger Door Ajar Malfunction
If not a scan tool would be the best way.
Ignition ON, observe the scan tool Driver Door Ajar Sw parameter while opening and closing the driver door. The parameter should change between Door Closed and Door Ajar
? If the parameter does not change, refer to Driver Door Ajar Malfunction.
With the passenger doors closed, observe the scan tool Door Ajar Switch parameter while opening and closing each door. The parameter should change between Door Closed and Door Ajar.
? If the parameter does not change, refer to Passenger Door Ajar Malfunction

Ignition OFF, disconnect the harness connector at the driver door latch.
Test for less than 5 ohms between the ground circuit terminal 8 and ground.
? If greater than the specified range, test the ground circuit for an open/high resistance.
Ignition ON, verify the scan tool Driver Door Ajar Sw parameter is Door Closed.
? If not the specified value, test the signal circuit terminal 6 for a short to ground. If the circuit tests normal, replace the BCM.
Install a 3A fused jumper wire between the signal circuit terminal 6 and the ground circuit terminal 8. Verify the scan tool Driver Door Ajar Sw parameter is Door Ajar.
? If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
If all circuits test normal, test or replace the driver door latch

To check your doors for leaking close the door on a piece of paper. It should stay in place, no slipping and should be fairly firm to remove with the door closed. To tighten them up, open the door and hold it open while pressing in on the top. It wont take a lot. Try again with the paper. If the doors are good then you need to look at the windshield and rear window as the culprits. they will need to be looked at by a glass installer and repaired there.

Could be resistance in one of the tracks, or the motor.
If the motor hits a resistance the door opens in case the resistance is a human.

From the owner's manual:

If your vehicle has

the dual power sliding doors, both doors will have

to be reset. To reset a door, do the following:

1. Check to be sure the power sliding door is

unlocked and securely closed.

2. Turn the ignition to LOCK.

3. If the power sliding door overhead console

switch is in the override (deactivation)

position, return to the activation position.

4. Open the sliding door using the remote

keyless entry transmitter, overhead console

switch, or passenger switch. Allow the door to

travel fully open.

If the door does not travel to the fully open

position, press the overhead console switch to the

override (deactivation) position and slide the

door fully open and closed. Check for foreign

objects in the tracks. Repeat the procedure starting

with Step 1. If the door resists travel to the fully
open position, see your retailer for service.

Door latch on door itself is in closed position if it will not close at all. In this case, open door and pull outside handle hard to pop open door latch. If you have door opening at random, door latch needs replacing or door catch on body is loose.

lube the hinges and striker rod, which is the piece that comes out of the door, when you open it.

Spray the rollers and pathway with WD-40. This lubricates the door rollers and also cleans the rollers and pathway which the rollers travel back and forth. The door upon any resistance opens protecting the occupants from being hurt in the doorway. This worked on my 2003 Windstar.

We have the same problem, just opposite doors - the passenger slider will close to 80%, but the driver still functions fine. There must be an easier solution than new wiring harness/motor??

When you replaced the vent window assy. did you seat the assy. into the door channel? Something is out of alignment.