Ooh see, i had this issue before. For us it was the the radio relay....

Hello Peter:
Four candidates in order of likelihood:

1) RPM reference sensor on top of transmission bellhousing

2) fuel system relay (resolder or replace)

3) radio suppression relay (clipped onto coolant recovery tank-- can swap with identical electric fan relay to test)

4) power stage (ignition amplifier)

Nothing here is expensive, everything is something that you can replace yourself-- the RPM sensor is the only part that requires any contortions to R & R...

Good luck-- let us know what fixes things!



--
Herb Goltz, Aurora, Ontario, Canada '92 245 w/124K mi, '92 945T w/200K mi

right after it stops, pull a plug wire and check for spark. You could have a failing ignition module- the thing on the driver's side inside fender, behind the headlights. It's easy to replace, and not that expensive.

It might be the engine harness starting to go. My 87 did the same thing before it died a few months later. It started occurring more often, progressively getting harder to start until it finally died permanently. Check the condition of the wires running under the Throttle body by your Idle control motor.
That is where most of them go bad.