Mitsubishi Repair: 1994 Mitusbishi Galant, mass air sensor, auto salvage yards

Question
I have a 1994 Mitsubishi Galant S and the engine  idle is very rough. Check engine light was on. The rear Oxygen sensor was replaced/ light is out and it ran slightly better. Now is worse than before and stalling.  A general mechanic said the problem is with the oxygen system, could be the computer chip, etc.. He disconnected the air computer system  at the air filter and it's idling better.  He recommended taking it to the dealer. $$$$$.  Any other solutions? --Katalex

Answer
Catherine,
There are many cases where the car's computer was the fault in older Mitsusbishis.  Read this article for further information:
http://90gsx.com/eclipse/cap/caps.htm

If your check engine light still comes on, take your car to an AutoZone if you have one locally.  They will be able to scan your car's computer for error codes for free.  Otherwise, you would need to bring your car to the dealership so they can pinpoint the exact problem.  If the dealership says you need a new ECU or Mass Air Sensor (MAS - the air computer at the air filter) then you might be able to save money by calling around to junkyards or auto salvage yards, and ask if they have used ones.  A new one from the dealeship will costs you hundreds of dollars.
Good luck!