Thanks for reply NVW. I replaced PMD and installed heat sync few years back.
It doesn't do it while cruising steady. Just when shifting to higher gear. Downshifting is fine.
I have a '94 Chevy 2500 6.5 with the 5spd manual. Can the accelerator pedal position sensor affect shifting from one gear to another? The reason I ask is when accelerating fast and up shifting the engine will rev up even though my foot is off the accelerator pedal & not engage the next gear...