I have a 91 mustang lx an the check engine light is on I plugged it in an it comes up multiple mis-fire so I replaced plugs,wires,coils at its still mis-firing wat else can I do to fix the problem any suggestions please let me know
Get the ICM (ignition control module) checked out. It's mounted on the side of the intake manifold. It's got a plug on the top and bottom and autozone or whatever should be able to check it out to see if it is any good.