I have a Silverado with a 5.3, a t56 and some boltons that has breakup under part of the throttle stalls when I push the clutch in or stop. Starts up just fine. Revs up just fine but anything under 2000 RPM and it's stutters and wants to die. Performance is all there has perfect fuel pressure above two thousand is what I was told by the dyno guy last month. Has injectors and pump. Tank seemed clean I can't find a vacuum leak with spray, hand hover, or a listen test. Oil looks fine. Corn is fine. Doesn't going to be leaking anything but it does have a little bit of white smoke because I believe the rings are going out... hey junkyard blocks. Still has I still has great compression but didn't do a leak down sooo.

 

Check the throttle follower, and throttle cracker tabs in the HP Tuners