2002 4.2L Same Problemwith P0171 and P0172
 

Ok I did alot of reading on here and tried alot of the fixes posted and here is my problems. The truck has the following codes, runs like crap all the time, sounds like it is backfiring throgh a carburetor (although I knwo it doesnt have one), stutters when going uphill or giving it more ghas to accelerate. I am sure everyone is familiar with these.

P0102 - Maf Sensor
P0171 - Lean
P0172 - Lean

So I smoked it, no vacuum leaks seen.. I used TB cleaner everywhere, no idle changes. I cleaned the MAF sensor, now it runs worse. I keep reading about the upper Plenum Gasket, and the new bolts the TSB talks about, would that be my next course of action?

"When all other options have been exhausted, and you have no other choice, then there is no choice to be made."

Sorry, couldn't resist. I would say that would likely be your next course of action. Is it still throwing the MAF code after the MAF was cleaned? Could it be the MAF is bad and needs to be replaced?

Yes it still shows the MAF code

All things considered, I'd say your MAF is probably bad...... Hopefully someone else will chime in to confirm or deny.....