454 TBI lean stumble on throttle tip in

[j_cst_10]

Hey guys, I appreciate any advice.

I have a 91 2500 2wd suburban (square body) 454TBI with the 4L80E trans. It intermittently develops what I can describe as a lean condition stumble (although that may not be accurate but almost feels like a carb with an accelerator pump issue). If you hold your foot on the accelerator at this point it stumbles and bucks depending on load. It appears when the truck is up to temperature. During warm up it is fine. And sometimes it doesn't do it at all!

The truck runs pretty rough when it is initially started and burbles and pops, but then smooths out and drives pretty much completely normal. You can power past the stumble if you put more foot into it.

I have done a simple tune up and replaced the temp sensor in the cylinder head and cleaned the TBI the best I could with spray cleaner.

Anybody else run into this with any of the 454's with TBI?