98 sunfire stalling

I have a 98 sunfire with a 2.2 auto with air. It runs OK, but then every now and then it just stalls. A mechanic told me it might be a MAP sensor. I hooked up an actron scanner and the car has no codes. If a MAP sensor was causing the car to stall would the check engine light not turn on and would it not set a code? I'm leaning towards a good tune up and a new cat. convertor. The car has 140,000 miles on it. I think the convertor is original. Would a plugged convertor set a code too or not?

Thanks Marc

I had the the same problem on my '96 sunfire 2.2l. chased that all over, previous owner said he changed the f/i's. Turns out he installed the cheap ones from autozone.?(bad move,very bad). The injectors were bad, changed them and everything works fine now. Seems the original problem was a bad ECT sensor. I found that and changed it first, helped, but he added to the problem. You know, when someone does something you can't eliminate it as the problem I guess.

If the cat was bad, it would be throwing a CEL for a low efficiency Bank 2 sensor. Its most likely a clogged fuel filter, injectors. But from my knowledge in dealing with these cars, it def. sounds like a fuel problem.

What is a good brand of fuel injector? The auto zone here sells bosch. What is a cheap auto zone injector? Does cleaning them with cleaner in the gas ever really work?

I put in AC Delco F/I's at about 1 C note ea. fixed it right up, and in the process of chasing this problem, i fixed countless other little problems.
As a side note, about 3 months after i had the car purring like a kitten,
my daughter let "her friend" drive it. Two curbs later, my car is totaled. Oh well. nobody was hurt but me(mentally) so i count my blessings.