'91 Mustang GT (ignition misfire when cold)?

Tachometer drops instantly and engine cuts off for 1/4 second or so every several seconds and continues doing this for around 5 minutes until the engine warms up.

This is not a single cylinder misfire, it's a brief, complete ignition system misfire.
It's not a loose spark plug wire, or coil wire.
All connections are clean and tight.

Now, I'm familiar with other ignition problems that are caused by coil getting hot and failing until they cool off. But this has frustrated me for several weeks troubleshooting this issue.

There are no check engine light codes.(scanned w/AutoXray 7000)
Running voltage is good. 14.3
Fuel pressure is 36psi running.

For Ford experts, is there a common problem that I should investigate, short of replacing a bunch of good parts with new parts and wasting money?

Mustang Driver2010-09-26T12:37:35Z

Favorite Answer

I would test the ignition module first. Maybe a cam sensor. I can't think of anything else that may be causing the problem.

toadyboy2010-09-28T01:14:50Z

more than likely the ignition module is getting hot and failing intermitently