Hi, our 2009 tahoe 2wd LTZ, 220k Miles is acting up. Been throwing parts at it and I am about over it. This thing upon first crank up either in morning or after work will sometimes go Into low power, have rough idle, no throttle. I can disconnect battery and the coue times I tried it, it would be fine after. Dealer said it was the converters, other codes led to TPS, and I think a switch. So...here is what has been replaced. TPS, some part of ignition (mechanic swapped), full new y pipe and new converters, new battery. Obviously the dealer is users and local mechanic just can't find the issue. Konda leaning toward more of the ignition.....just don't know what to replace. I hate throwing parts but it is tough to locate the problem. I appreciate any assistance.

 

It's all about the codes the computer records today. Codes point the way, if none are set it's a guessing game until some show up.
Only way you are going to self fix it is by having a quality scan tool. Scan tool is more important than hand tools today.
No shop is going to throw guess parts at it as they cannot stand behind their work.
I would suspect harness connections, poor grounds or something on that order with a high mileage truck.

 

Yessir that is why I went to the dealer who was just positive it was the cats. Very frustrating!!!! I will start checking what you said. Done with dealer!

 

Gas pedal assy is a common item, especially in high mileage. Express vans in my old job would start having issues with them after 150k miles. But they usually set a code and engine light.
And the battery disconnect would reset it an let you limp into the shop.