Outer Limits 4x4 Board

I am hoping someone can help me or has heard of this before:
Have '94 NJ Pajero 3.0L V6
Driving along happily about 6 months ago and motor just stops running.
Cranks but won't spark. Motor cools down for 1/2 hour and starts runs for about 10 mins. Let cool down to cold, starts, runs 10 mins, etc..
Check all elec connections, run tests for engine management as per Gregory's Manual found nothing.
Found no spark sometimes, replace power transister (ignition module) - still no different.
Replace coil (with Bosch) runs fine for 5 months, then it all happens again.
Replace coil runs fine for 4 days.
Replace with genuine coil runs for about a day, then the same.
Get computer checked out, mechanics, dealer and auto elec to look at. No one can find a problem.
Got it back home and has been running fine for last week.
Can anyone shed some light on this ???
I have run out of ideas.

Crank angle sensor? (I presume it has one?) If the ECU doesn't see the engine turning it won't fire?

Scott

have you also changed the plugs and leads?

Thanks for the feedback. I have been think it may have been the computer, but thought I would see if others had similar problems. I will check out the crank angle sensor it got to be cheaper than a new computer.
Has had new plugs and leads.