Reduced engine power 2004 chevy tahoe 2x2. have rreplaced 2 modules and tac still doing it everytime i drive it any answers?

engine losing power sign ??? .You mean ENGINE POWER REDUCED ? This has to do with electronic throttle control -Throttle Actuator Control (TAC) System Description

The throttle actuator control (TAC) system is used to improve emissions, fuel economy, and driveability. The TAC system eliminates the mechanical link between the accelerator pedal and the throttle plate. The TAC system eliminates the need for a cruise control module and idle air control motor. The following is a list of TAC system components:
• The accelerator pedal assembly includes the following components:
- The accelerator pedal
- The accelerator pedal position (APP) sensor 1
- The APP sensor 2
• The throttle body assembly includes the following components:
- The throttle position (TP) sensor 1
- The TP sensor 2
- The throttle actuator motor
- The throttle plate
• The engine control module (ECM)

TAC System Default Actions/Reduce Power Modes
There are 2 reduce power modes that the engine control module (ECM) can default to if an error is detected in the throttle actuator control (TAC) system. If an accelerator pedal position (APP) sensor 1 or APP sensor 2 circuit fault, throttle position (TP) sensor 2 circuit fault, or if a TP sensor 1 circuit fault is detected with some APP angle, the ECM goes into one of the 2 reduce power modes. In this mode, the engine torque is limited so that the vehicle cannot reach speeds of more than 100 km/h (60 mph). The ECM remains in this reduce power mode during the entire ignition cycle even if the fault is corrected.
If there is a condition with the throttle actuator control circuits, throttle actuator command vs actual position fault, return spring check fault, or a TP sensor 1 circuit fault, the ECM goes into the other reduce engine power mode. In this mode, the engine speed is limited to 2,500 RPM and the 3-6 fuel injectors are randomly turned OFF. At this time the Reduced Power indicator is commanded ON. The ECM remains in the reduce power mode during the entire ignition cycle even if the fault is corrected. Observe, if a TP sensor 1 or throttle actuator control circuit fault is present at the time the vehicle is at idle, with no accelerator pedal angle, the engine may stall.
© 2022 General Motors Corporation. All rights reserved.

You need to have a qualified repair shop check it out.

Sorry , no reset for the fuel pump . Reduced engine power message is for the TAC - throttle actuator control system . Electronic throttle control . Reduced Engine Power: Throttle Actuator Control (TAC) System Description for the 3.6L engine or Throttle Actuator Control (TAC) System Description.TAC System Default Actions/Reduce Power Modes
There are 2 reduce power modes that the engine control module (ECM) can default to if an error is detected in the throttle actuator control (TAC) system. If an accelerator pedal position (APP) sensor 1 or APP sensor 2 circuit fault, throttle position (TP) sensor 2 circuit fault, or if a TP sensor 1 circuit fault is detected with some APP angle, the ECM goes into one of the 2 reduce power modes. In this mode, the engine torque is limited so that the vehicle cannot reach speeds of more than 100 km/h (60 mph). The ECM remains in this reduce power mode during the entire ignition cycle even if the fault is corrected.
If there is a condition with the throttle actuator control circuits, throttle actuator command vs actual position fault, return spring check fault, or a TP sensor 1 circuit fault, the ECM goes into the other reduce engine power mode. In this mode, the engine speed is limited to 2,500 RPM and the 3-6 fuel injectors are randomly turned OFF. At this time the Reduced Power indicator is commanded ON. The ECM remains in the reduce power mode during the entire ignition cycle even if the fault is corrected. Observe, if a TP sensor 1 or throttle actuator control circuit fault is present at the time the vehicle is at idle, with no accelerator pedal angle, the engine may stall.

Engine power is usually reduced in response to a fault being registered by the computer management. A fault that would affect exhaust emissions would usually switch on the check engine light and so your engine fault is likely to be outside the scope of OBD2 and need dealer level software to diagnose.

Well an oil change is probably not the cause.
What IS it doing? You're telling me what it isn't doing...
Does the motor rev up?

Throttle Actuator Control (TAC) System Description
You have APP- accelerator pedal position sensors or one of the Throttle position sensors is going bad ! In the (TAC) system ! This is drive by wire or electronic throttle control . If you take it to the dealer or a ASE certified repair shop they can check the DTC'S - diagnostic trouble codes ! This is nothing for a DIYer to mess with ! This system can set 7 different DTC'S

Reduced Engine Power Mode When the PCM detects a condition with the TAC system, the PCM may enter a reduced engine power mode. Reduced engine power may cause one or more of the following conditions:
?€¢
Acceleration limiting--The control module will continue to use the accelerator pedal for throttle control; however, the vehicle acceleration is limited.

?€¢
Limited throttle mode--The control module will continue to use the accelerator pedal for throttle control; however, the maximum throttle opening is limited.

?€¢
Throttle default mode--The control module will turn off the throttle actuator motor and the throttle will return to the spring loaded default position.

?€¢
Forced idle mode--The control module will perform the following actions:

-
Limit engine speed to idle by positioning throttle position, or by controlling fuel and spark if throttle is turned off.

-
Ignore accelerator pedal input.

?€¢
Engine shutdown mode--The control module will disable fuel and de-energize the throttle actuator.


Drive by Wire Function and Diagnostics by Wells

Here is the definition of the code.

Possible causes - Faulty Throttle Actuator Control (TAC) module
- Throttle Actuator Control (TAC) module harness is open or shorted
- Throttle Actuator Control (TAC) module circuit poor electrical connection (loose or broken wires)

P1516 CHEVROLET Description The Throttle Actuator Control (TAC) module contains data which is essential for proper TAC operation. The TAC module continuously test the integrity of this data. When the TAC module is unable to write or read data to and from Random Access Memory (RAM), or the TAC module is unable to correctly read data from the flash memory or and internal TAC module processor fault is detected and the Detected Trouble Code (DTC) is set.
Read more: http://engine-codes.com/p1516_chevrolet.html#ixzz286Gl3cSo

Most auto parts stores have Scanners that can read the actual Codes causing the check engine light- usually for FREE. Google the Codes to determine what needs fixed.

Do not continue to drive it, as it may cause permanent damage!

GL,
Td

Hello,
Yes it sounds like you need a Throttle Actuated Control also known as a TAC. The TAC module or the TAC sensor (pedal assy) then there is the TAC throttle plate assy. There is alot to do in the process of corectly diagnosing this system. I recomend you take it to a qualified technician.
I hope this helps.
Roy

P1516 Throttle Actuator Control(TAC) Module Throttle Actuator Position Performance

This is your problem and should be taken in to chevy for repair

It was reduced engine power. I'd bet you have some "TAC" codes, Unless you are very mechnicaly inclined then you need to end up at a shop. They have been rewiring the tac modual and replacing the trottle bodies to fix this problem.