Need Help Bad! Mechanic cant find problem!

[NotchJohnson]

Hey guys, my dad took my car to the mechanic yesterday and they looked at the car for 7 hours and couldnt find what was wrong. If you didnt see my post from last week, the car started acting up a little at idle at first. This was around a month ago. After only missing and surging a little bit at an idle, the car began to stall out at idle, and also cut out for a spilt second and stutter while cruising at low rpms. Now the damn thing runs ok while cold, but once it heats up it hardly runs. It surges like crazy at an idle, constantly misses and hesitates at cruising speed, and sometimes kicks in and goes and sometimes when i punch it it hesitates, revs to like 3 grand and even backfires sometimes. WTF! This is really pissing me off considering im in school 200 miles away and rush home every weekend to figure this crap out. So far i have checked the egr, checked for any vacuum leaks, and someone even told me it might be the tps, so i even went out and replaced and volt-tested it. I even went further and replaced the cap and rotor and all the plug wires. No difference after any of this. Another thing that is interesting is when the car first acted up at all, I was driving in the rain. I find it hard to believe this is just a coincidence, but it may be. Have you guys ever heard of anthing like this before? The mechanic also said that it must be a problem with the computer. He said the options I have are to either get a new comp. and harness or switch to carb. What's up with that? Im really pissed. If you guys can help me out at all, either by giving me some input, or slipping some dynamite in the car late at night, I would really appreciate it. Thanks Alot, John