"Reduced Engine Power"

So after all the fixing and fixing of my yukon close to $2000 worth I am now getting "reduced engine power" flashing every other day and my engine loses power and wont let me go over 5 mph. I press the gas pedal and the rpm's will go to about 800 but that's all. I have to shut the truck off and wait a few seconds then crank and hope it works fine, sometimes it does sometimes it doesnt.. When it does run fine after the engine loss the "reduced engine power" flashing is gone but the check engine light remains. I took it to autozone cuz i just hate spending $90 to get my truck looked at from the dealer especially since i have done it 3 times in the past couple of months. They said they couldnt read any codes and just nothing was showing up.. Does anyone have any suggestions for the cheapest parts i can try replacing to see if that's the problem.. Like throttle body sensor, o2 sensor?? I dont know any help would be appreciated. Im wanting to sell in a couple months and wont get anything for a truck that wont run

get out, dis-connect battery, wait a few minutes, let it reset then reattach. If it does it again, there is something wrong. Have Advanced auto, etc run the codes.

I will go try that right now since it did it to me twice within 3 miles. Hope this works

sounds like it may be an issue, but at least that will clear everything stored in the system.

check and make sure your throttle body isnt unplugged or lose. and any other connections under the hood. i had this problem with my silverado and the TB was the cause

Tried the disconnect and so far no problem or lights. I will check for anything loose and give it a day or two, hopefully I'm not having to put money into it

cool...at least your 'clean' now if you have to run codes.

i'd check the grounds on your computer. mine was acting like that or just acting like there was no battery connected at all when you put the key in. turned out to be the bcm and they said the ground for the ecu was all messed up too