1992 Dakota Engine Shutdown

92 Dakota 3.9L
Starts and runs great. Engine shuts down, usually within first 30 minutes after starting. No shutter, just as if you turned off the key.
It has not been an everyday occurance.
I can wait 2 minutes or spray brake cleaner in the intake and it will restart.
It will run the rest of the day and never happens again on the same day, even with multiple restarts and driving 100 miles
I have installed a new ASD relay, new fuel pump relay, new fuel pump, new crank sensor and new air valve controller on the intake.
This has been a hair puller for me and my mechanic. They can't seem to catch it when it happens.
Any suggestions are welcomed. Thanks

Update
Yesterday the engine shut down while going downhill.
I left the key on and as is slowed down to about 40mph, I put it in 2nd gear.
It re started after a few seconds and kept going the rest of the day.

Don't know if you were able to get this fixed yet, if not, suggest it may be idle air control valve. My Dak did the same thing awhile back...changed this... Stopped shutting down.