Recently, my stock 1996 2.4L Cavalier LS convertible (70k miles, manual transmission) started to sometimes hesitate on acceleration, but only when the RPMs are below 2k, and I think only before the engine has fully warmed up (though the outdoor temps are about 60-70 degrees). Upon acceleration, the engine just cuts out for a split-second and then resumes normally. I only seem to notice it in 2nd or 3rd gear. Othewise the car sounds, smells, idles, and behaves normally. No CEL.

I just replaced the vacuum line to the MAP sensor but that didn't help solve the problem.

Everything else on the engine is original, except the water pump, thermostat, and tensioner for the timing chain.

Any ideas?

Fuel system it sounds....maybe injectors. My buddies Z24 had a similar problem and it had a tore o ring and we fixed it that way