detroit305

Running out of ideas, can someone help: 86 305 TPI, original owner, 54,000 miles. Engine wouldn't run after start and key return to run position, concluded was only running on cold start injector. Steady 42 psi fuel pressure. No trouble codes. Installed reman ECM, engine would then start and run, however idle higher than normal with periodic large drop in idle speed to almost stall and then resume, after 5 min or so complete stall. On road engine cuts out and resumes. Still no trouble codes. With IAC disconnected same symptoms but even higher idle speed, with MAF disconnected same symptoms but rough running engine. Removed belt from alternator, same symptoms. Volts at battery steady 13.8 with engine running. Clean tight ECM ground at back of DS head. In diagnostic mode various relays etc start and stop at random, check engine light erratic. Haven't been able to reactivate my old Diacom software so hoping someone has seen this before. Thanks

IROC-T

Curious, have you checked or replaced the ignision switch,(not the key switch)down at the lower end of the colum. When these act-up little vibration can cause all kinds of problems. Worth a check...

detroit305

Ignition switch - good idea, I'll let you know what I find