Problem with 93 gt

the car will start and just start to fire up and it dies off.. I checked the battery and its fine.. I have the hei mod. The kicker is that the beast fired up for some odd reason yesterday and I could actually drive it.. The only thing was the idle was kinda jumpy and when I punched the gas it sputtered a bit and back fired.. I replaced the plugs/rotor/disty cap. whats your guys idea?

Alternator, belts, Coolant system are my only guesses. OR something this major just take it to a pro.

check to make sure that you have no air leaks between the MAF and the throttle body. also make sure the plug on the MAF is plugged all the way in. by the way, what is hei mod

Ok well now the bad boy starts but its sputtering really bad.. I can keep it alive as long as I give it some gas.. I drove it down the street and back and she was stuttering and backfiring pretty well.. could I have a bad sensor or does this occur from something else?

It could be a few things; if the TPS (throttle position sensor) has knocked out of adjustment, The MAF sensor is stuck or not working correctly. make sure the cone inside the MAF moves easily and smooth when you press on it and returns to the seated position when released. If you still have the stock elbow that connects to the Throttle body make sure it is not cracked and be sure the clamps are tight. The stock elbow becomes stiff and brittle with age and has a tendancy to crack. make sure that the vaccum line and the blowby line, which are on the elbow, are in good condition. Hope this helps, I am better at trouble shooting when I can hear and see the problems.

Please let me know what the HEI mod is, might be the problem.