TBI woes

[ChevyTech]

Originally Posted by 66gmcguy

Another thing is when accelerating, I have a very distinct, but momentary misfire at a certain RPM. It only happens under light to moderate acceleration though, right at around 2200-2300 RPM, and it's only for a split second. The best way to describe it is it feels like the engine shuts off for a split second then turns back on almost instantly. It doesn't feel like a typical lean-sputter, or backfire. I thought maybe this was a TPS problem, but it does it on all three TPS sensors that I've tried, all at the same RPM under same conditions.

You have not mentioned anything about the distributor yet.
I would try a different Ignition Control Module in the distributor.
It sounds to me like the module could be switching back to the base timing mode for a second.
When you are in the distributor make sure the distributor shaft is not loose and can wiggle sideways.

These distributors also have problems with the shaft losing its magnetism but that usually shows up as a hard start or problems at lower RPMs.

A Cracked insulator on a spark plug can cause that same sensation. Also a torn plug wire boot. I usually could feel this best at a very light acceleration at about 40 MPH