Really bugging me, 1990 D150 with a 3.9 over 140k miles.
Intermittently= sometimes high RPM, sometimes coasting with clutch in to a light, sometimes three times a day, sometimes not for a week, it will die, and usually restart just with compression, but once died and I had to crank it.
Has full tune up, fuel pump and filter, and timing chain all within past couple months for different reasons, but all after this started.

Any ideas would be appreciated

 

man, could be alot of things. first think i would check would be that your battery cables are in good shape all the way through and check/clean all battery and chassis grounds. hope this helps

 

Iac (idle air control) You are right at the mileage when mine quit.

 

Thanks guys. I replaced the Hall Effect sensor and hat cured it. I had no idea the Hall could give an intermittent issue like this, unlike other types of pick up coils I've dealt with.

 

Just an update, the truck ran great since my last post, then last week it died and just wouldn't recrank.
Ended up being the ECM this time, LOL