My 07 Tahoe consistently shuts down and says reduced engine power . I changed the throttle position sensor and it drove for a day . Then I changed the accelerator position sensor & it drove for a week but if I put the truck in reverse low engine power would almost immediately come on and the truck would shut off . I would turn it off for a few minutes & drive off going forward and it would do fine for the day , just couldn’t put it in reverse . After changing the accelerator position sensor sometimes there would be no check engine like on the dash at all. At one point there wasn’t and the truck still reverted to low engine power & Shut down going 70 mph on the highway. Took it to autozone & the reader only suggest replacing harness but no specific harness. Any help as to what the problem could be ?

 

I didn't know readers gave prescriptions for parts.
The diagnostic scanner should have given you a trouble code. If not then maybe you need a better one. Try Oreily or Advance auto or some other.