Mitsubishi Repair: Problem with 91 Eclipse, engine cranks, vacuum leak

Question
I have a 91 Eclipse, 1.8L, automatic, 4cyl, with 109k miles...It has seen at least 5 mechanics in the last couple of months.  I have had the O2 sensor and the idle speed control changed, and the problem hasn't been fixed, and no one has found anything else to be wrong.  This is what happens.  The car is very slow reaching 30-40mph, and sometimes I can feel a rough shifting/downshifting.  After the car has warmed up and has been running for about a half hour it starts acting up.  The RPM's will suddenly drop to zero, the engine will still be on, but I won't have any power in the gas pedal. After a few pumps on the pedal, the idle returns to normal.  After running the car like this, when I try to come to a stop, the car will just lose all power and shut off.  There is no warning like a shudder or anything, just a click...and thats it.  Sometimes it will start right away, other times it will take 5-15 min before it starts again.  During the period of the car not starting, the engine cranks, but will not turn over, and there is no spark from the wires going into the engine.  I have read the other entries and heard things like the TPS and other sensors...but none of the mechanics have mentioned any of this, and I told them exactly what I've said here.  They have done the engine diagnostic and thats what made them change the O2 and the idle control.  My engine lite has never came on and I just had a tune up and oil change. Someone said something about a vacuum leak, but others disagree.  I am just wandering what you can gather from this because I really have no other options.  Any advice or help will be greatly appreciated, thanks for your time.  

Answer
Pamela,
A vacuum leak would not cause such a severe issue as the one you mentioned.  Neither will a bad O2 sensor or idle speed control.  It sounds like your problem is electrical.  Not with the spark plugs or other ignition component, but with your car's computer itself.  Read this article for furhter information:
http://90gsx.com/eclipse/cap/caps.htm

If your ECU is malfunctioning, you will have all sorts of intermittent problems, and most mechanics will not even consider its the computer's fault.  Your check engine light will not come on, because as your comupter sees it, everything it fine.  Your transmission also has its own seperate computer called the transaxle control unit (TCU).  It would be wise to have that checked as well.  Do not purchase any more parts for your car in attempts to fix it until you have a trained technician inspect your car's computers.
Good luck!