I have checked and\or replaced the following:

plugs
wires
injectors
coils
fuel filter
fuel pressure
maf sensor was replaced a year ago, dont know how to test??
vacuum leaks
cleaned throttle body
transmission
AFR good
New O2 sensors

I get a stumbles in these senario's

just taking off, real light throttle, will stumble if I hold throttle just barely open.

Highway speeds, TQ converter locked, steady rpm around 2200. If I lightly start to add more throttle I get a stumble. If I hammer it I dont get a stumble.

Truck runs great, strong revs fast and pulls hard. What else could I check???

 

Pump?
Did you check the fuel pressure under a load or just at idle?

 

I'm gonna call it the throttle body position sensor of sorts. You are drive by cable so it's maybe on the TB.
Can you borrow another TB?

 

I checked the TPS and I get .5 volts at closed throttle and 4.5 volts at WOT. I think this is within specs.

 

I checked pressure under both. I am at 58 psi idle, no vacuum attached, with vacuum attached it drops to 52 psi at idle. It climbs under load all the way to 66psi under boost.

Like I said it is strange as the issue is light throttle light load and light throttle heavy load both but always small throttle openings.

 

I tested the stumble this morning before the truck was up to full temp and it doesn't stumble. What could cause this that changes as the truck temp reaches full temp??

I run a 160 thermo so the max temp usually sits around 174 on the scanner.

 

My truck seems to stumble right after it shifts to second under light throttle. Let me know if you find out what is wrong with yours. I haven't logged mine yet so I don't have a clue what could be wrong.

Truck is 04 GMC Sierra ECSB

 

had same issues on a friends truck, it was a small crack in the porcelain of a spark plug.

 

I had it a few times before full temp less than a mile from home. Taking a right from a full stop and gently pressing the pedal it would stumble in 1st gear and take off or clear up the second I let off. Maybe happened 5 times over a month.
I have an 05. I took the gas pedal out and tested the position device and it was ok. I cleaned the TB real good and it has never returned.
Not sure if I did anything to rid of it or not. Good luck.

 

IWish that was all it was. Already tried new plugs no change. I have a new maf comming, I think the slight oil blowbye of the turbo is hard on the sensor.