Computer could be part of it. I had a 92 Mits Galant that when colder air or foggy weather the car would run rough and quit. It'd take ten minutes of cranking to get it to re start only to get up to 20 mph to have it stall again. It's made my hour and twenty minute ride up to three hours to get home. Trust me I was glad to see it go when it did. Anyway, what I had found out the first time when I was trucking down the highway at 70 it dies at speed. So trying to decifer the problem and going through replaced timing belt and pulled the head to inspect the valves. I put it back together and it never ran right again. I replaced the compuer with a 500.00 rebuilt one and it still ran like BLAH_BLAH_BLAH_BLAH. I'd get going and it would quit. so I started to go through everything. Ignition module, distributer, coil, plugs, wires, throttle position sensor, idle speed sensor, throttle body, mass air flow sensor and nothing. Finally I was done with it, it got parked and sat all winter. Finally in the spring one last hoorah I posted for help on Craigslist looking for a used computer just so I could troubleshoot it and see and a guy an hour North of me came back saying he had one. He drove down, we plugged it in and after 3000.00 dollars worth of work and labor it came down to an ill rebuilt computer which by then was to late to send back. So I sent it to someone my friend knew and 25.00 later the car was running like a top.
Only to have the frame rust out the following year...... Oh well.
Check the computer on it and see if that may be the problem... Good luck!!!