Mitsubishi Repair: 94 3000GT sl heavy misfire, fuel pressure regulator, air fuel mixture

Question
I have a 94 mitsu 3000gt SL with ~180k miles and a manual transmission recently i drove from Martinez to Hayward and made it there with no problems when i was about to head home i was at a light on a bit of an incline when i was going to drive forward the car shuttered like i didn't put enough gas and puttered then started sounding Really bad so i pull over and turn it off.. turn the car back on and it idles at 500-700rpm really rough so i open the hood and find a vacumline to throttle body was disconnected so i reconnect it and try again and made no difference so i took it to a shop and they said it was sparkplugs and since it was late in the day they couldn't fix it .. so i did it my self when i was done the car idled fine and drove like normal (the engine was cold at this time) i made it about 3/5s of a mile and at a light same thing happened so i get a tow home after the car was off the truck i started it to park it and it was fine once again so the next day i drove it and samething happened so i changed the sparkplug wires and it drove fine i drove it for about 45 minutes after changing the wires and it was completely normal the next day drove it maby 1.5 miles and same thing happened again i believe it might be an ignition coil or possibly clogged fuel filter .. im trying to sell the car so a quick answer or suggestion would be greatly apprieciated!!

Answer
Neil,
This can be a number of things, including a bad filter or even fuel pump.  Though I would guess you problem is electrical as it happens sporadically.  Also due to the fact that it tends to happen most when after the engine reaches normal operating temperatures.  Your car's computer takes over on for regulating the air/fuel mixture once the engine is warmed up.  So the problem may be in an air intake sensor or possible fuel pressure regulator.  You should check the car's computer itself.  Read this article for further information:
http://90gsx.com/eclipse/cap/caps.htm

If the ECU is damaged, it can cause various idling issues without any indication from the check engine light.  That's worth a shot checking.
Good luck!