Hesitation and slight popping during acceleration? Why?

[MLMike25]

93 Notchback 5.0, AOD. No real mods (K/N, Flowmaster exhaust). Less than 49K original miles.



Let's say I'm in 1st or 2nd gear, accelerating normally, and then I floor it, I feel LOTS of hesitation and a pop or 2 (not a backfire) from the exhaust. It takes a few seconds before the car starts really responding (this does not happen in 3rd gear).



I thought it might be my injectors and I've been trying to clean them, but I think its probably something else 'cause it isn't getting any better (with Gumout fuel system cleaners).



What could it be?