i've been trying to tune a tahoe for a guy and its not going so well. the fuel trims are at +7-12 (with stock tune) and if you add that to the ve table then log it still tries to add it in. i'm not sure what going on here. the tahoe is bone stock with 179,000 miles. i think his O2's are not doing so well. they are stock also. and at one point he did have a k&n panel filter on the truck. its stock paper right now. he tried to "burn" the crap off the O2 sensors because a (ford) guy i know told him it would work. i told him it sounded like a dumb idea but he tried it and it didn't do a thing. so what should i have this guy do? i'm thinking new O2"s and clean maf. but what else? could it be a bad spray pattern? being that the injectors are so old. i have a set i was gonna let him run, but they have been sitting in my tool box for a very long time.

 

I going to say bad O2 sensors. I replaced mine at probably 90k even though I was getting a CEL; it ran and idled much better and I picked up 1.5 mpg. Running a bottle of Techron through to clean out the injectors might not be a bad idea, I would change the fuel filter after though (I always feel like it breaks up stuff in the tank that gets sent to the filter).

 

also, his truck takes two to three times to start. some times first try but most of the time not. i forgot he has a inline filter. mine didn't have one stock, good point. i agree with the breaking up of **** in the tank. he also has a thing where if he stops at a red light and puts it in neutral it want to idle at 1000rpm.

he had a cel for knock sensors, but they have been replaced just never code cleared. also a cel for someting with idle, forgot what it was. so his iac may be clogged or dirty.

 

I would have him do a complete tune up, from the sound of it he is long past due. Plugs and wires, fuel filter, and the o2's, then see where its at. Also, I would remove the throttle body and clean it real well along with the iac as you said.