Mitsy's have a very common fault with the ISC (idle speed controler) or stepper motor, they have a series of coils inside that have power applied at verious times to open and close the idle valve, sometimes (very often) these coils or one in particular will burn out due to it being powered more than it should be, the car will run fine until the battery is disconnected (which looses the ECU's memory)
A new ISC motor normaly costs about $300NZ + fitting and setting up.
UCP's Biggest Murph Fan, dont tell him though, he might think im a bit gay.
Thats me and Murph on the left. Im the taller one.