I have a real head-scratcher here, so please hear me out: 89'F-150, stock 302, M5R2 4x4.

The issue is that when I am driving along with the engine anything but cold, as I come to a stop and go in neutral (happens at any speed) my idle RPMs will drop down to 500-400, and maybe ping up and down just a bit until I come to a complete stop. Giving throttle does not affect the condition. 1 out of 100 times it stalls. The oddball thing is that my idle RPMs do this until the instant I roll to a complete stop. The instant the truck comes to a halt, the RPM's surge upwards of 700 for an instant (my closed loop warm idle) and then settles back to 700. I would like to add that during cold start my RPM will dip very low until the idle picks up to warm up, IDK if related or not. I do not anticipate being able to duplicate this condition in my driveway as it only happens going into neutral at speed.

Obviously I should pull codes but for some reason (bad connection, wire?) I cannot and the CEL comes and goes. Otherwise she runs fine and is well served as my daily driver.

So what tests and parameters can I check/verify in order to narrow down the problem? Also, as a beginner with Ford SD and engines in general, if anyone could illustrate how to run the tests i may need to do or point me in the right direction of some useful info; that'd be swell!!!

Cheers guys!










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