While driving at about 65, my car occasionally hesitates. I just had the ecm reflashed for a p0202 code. Also, the ac was on when hesitation occured.

run the fault codes
possible faults include the vacuum actuated turbo vane changer not changing according to the manifold vacuum, fuel pressure problems or faulty cat converter blocking exhaust

Possibly the ECM. You might check with the dealer regarding updates to dealer service bulletin 902-302-6E.

Another service bulletin:

Engine stall, long cranks & deceleration
surge 1990-93 (33-65-06 & 93-291-6E)

This may involve a process of elimination. Here are some possibilities:

Chevrolet Beretta Engine hesitates during acceleration Inspection Costs...

You might want to check this site for some tips and solution.

Misfire Hesitation Please Help

im having the same issue. I think the problem is the tcm but after installed make sure you get clear the codes and reprogram the computer

ECM needs to be reflashed per TSB.

You set the gap at 20 sould be 16,a hesitation or occasional miss is not from the points or condensor, its from the craburator,its a power valve or your float getting the hesitation can be the secondary not feeding at wide open throttle, the carburator is faulty, and plus todays fuel is not meant for carburators

Have you had the engine scanned for trouble codes? You didn't say anything about a check engine light, but I think the computer may have some stored trouble codes that would have something to do with the problem.

Seems as though you've got it covered...Try adding "SeaFoam" ($9) from Advance Auto Parts and add it to your gas...drive for at least 100mi. Good Luck

check for damage to the wiring going to the trottle positon sensor. and is the cap and rotor ac delco because i have had chevy trucks give me problems with non delco ignition parts.

A pop and hesitation is likely a backfire. The hesitation around 40 and 50 would be in keeping with that theory. There are several reasons you might be getting backfires and hesitation. If your ECM is adjusting the engine to run too rich this could happen. Misfiring might be occuring. Timing could be out. But one of the most likely is a restricted exhaust, likely due to a plugged, damaged or worn out catalytic converter. In some cases the converter may be bad enough to be giving you some performance problems, but not yet quite bad enough to signal an error. A vacuum test can help confirm whether this is exhaust related.