Mitsubishi Repair: 1991 Mirage, 1.5L, Automatic (Stalling Issue), coolant temperature sensor, radiator hoses

Question
Hello,

I recently "resurrected" a 1991 Mirage w/1.5L engine and an automatic transmission.  

When I purchased the car it wouldn't start (no spark).  I did a compression test, and the results were as follows: 130, 100, 60 and 130.  Due to the poor compression, I installed a used engine (from a 1991 Eagle Summit).  I now have good compression: 175, 155, 165, 175.  

The car still wouldn't start, however, so ... I installed a new distributor and ECU.  The car started and ran, so (in order to make the car reliable) I changed spark plugs, spark plug wires, fuel filter, timing belt, thermostat, all drive belts and radiator hoses.  The car's alternator and battery test ok.

The car drove great for a couple of days.  Now, however, I start the car, drive 4-10 miles and the car dies.  Sometimes it will restart after a couple of minutes and sometimes it must sit for 20-30 minutes.    

The car's ECU is located behind the dash, on the passenger side of the car.  The transmission control unit (TCU) is located behind the dash, directly underneath the radio.  There is a clicking noise that begins shortly before the car stalls.  

Is it possible that the TCU (the unit I have not replaced) could be causing the car to stall?

I have spent much more time and money on this car than I had hoped to, and I am really getting frustrated.  Any help you can give would be greatly appreciated.

Thank you in advance.  

Answer
Lance,
That clicking noise coming from the ECU is not a good sign.  Read this article for further information:
http://www.90gsx.com/eclipse/cap/caps.htm

Your car seems to be showing some classic signs of a failing ECU.  Though this can be caused by a faulty engine coolant temperature sensor as well.  But I'd recommend pulling the ECU and examining it for any damage to the circuit board.  If it is badly damaged, it would most likely need to be replaced.
Good luck!