1999 Vortec 454 Running rough and drivning me nuts

[454cid]

The truck stalls when I unplug the MAF. Also have a P0135 cide now.

Did you restart it? I've had it stall too, but it stayed running after I restarted it a time or two.

 

[Mangonesailor]

The truck stalls when I unplug the MAF. Also have a P0135 cide now.

o2 sensor heater circuit.

Sounds like you have a wiring issue. What is the history on this truck?

 

[montess85]

Got rid of the p0135 with a new O2 sensor. Truck has same issue. Now I have a P0171 Code. I have checked the O2 on a scan tool. I added fuel(carb cleaner) to the engine and the STFT changes on both banks when I spray. It goes from about 0%-3% to about -15% when I spray carb cleaner in it. The LTFT is all out of wack on bank 1. Its maxed out at 25%. So this test shows me that the O2 sensores are working and that there is actually a lean condition. I have looked and checked multiple times for a vacuum leak. Tried spraying carb cleaner around and even used propane. Engine doesnt change at all when I do this. What else can cause this lean condition?