Mitsubishi Repair: 1995 Mitsubishi Eclipse, valve cover gasket, mass airflow sensor

Question
95 Eclipse, 2.0, GS, manual--hello I have a couple of problems with my vehicle.  First off they are all intermittent, problem with starting ( does not maintain idle, have to keep accelerator pressed for a while), stalls when clutch is depressed, on highway driving speeds vehicle bucks (Check Engine Light flickers on/off when this happens but does not remain on, therefore computer diagnostic has been unable to pickup code, vehicle starts back up when it stalls by the way.  Known necessary repairs include the following: valve cover gasket is leaking again (pool of oil in spark plug well #4), head gasket has minor leak (have not replaced on advice of my mechanic, who happens to be the lead tech at Mitsubishi dealership) in his experience he has mentioned that within a year it will leak again, this is based on bad design of gasket itself. He is stumped as well on this. He has mentioned it could be a # of sensors but would hate for me to spend $$ on process of elimination.He has mentioned that the stalling when clutch is depressed is symptomatic of Idle Air Control sensor, but not the jerking at highway speeds. He has also mentioned it could be ECU, Speed Sensor, Mass Airflow Sensor.  I have replaced both Oxygen sensors, crankshaft sensor, one of the relays on the firewall that caused my car to completely stall and refude to start-up. Other issues include new belts to squeal at start-up, especially w/AC in "on"position, buzzing or light tone sound coming from behind radio location at start-up?  Fuel/air filter, PCV valve have also been replaced.  Thanks for your time in advance----Eddie

Answer
Eddie,
The ECU is a definite possibility and should be checked.  There was a well known issue with Mitsubishis produced between 1989-1994 that had under-rated capacitors in them that would eventually leak, corrode the circuit board, and cause all sorts of random and strange problems with the car.  It's very possible this could have happened in your ECU.  The ECU is located behind the radio, and may be causing that buzzing noise you're hearing.

Idle problems usually are caused a faulty IAC.  Though bucking at highway speeds can indicate one or more spark plugs not firing or intermittent fuel supply problems.  It's possible your #4 plug is having a difficult time firing if its getting soaked in oil.
Good luck!