Recently the check engine light came on in my 2001 Mustang, which as 82000 miles. When I got the reading, it said there was a cylinder misfire ( in no. 3). There are new spark plugs (about 5000 miles ago). I wonder if replacing the coil would be the next place to go to solve the problem? What other sources of misfire shoudl be investigated?

 

Had the same issue with our 2001 with the 3.8L engine, but it only had 5,000 miles on it. Coil be coil pack or even thou basically new could be a spark plug (most common cause) as I have seen new plug bad right out of the box. Our issue was a bad injector causing the mis-fire. May or may not be your problem. Have you ever run any injector cleaner thru your system?

 

Agreed. Try running SeaFoam in your tank to clean any possibly dirty injectors. If that doesn't work, try putting the old plug back in or a new plug in that position to see if it changes anything.

 

I have not tried any cleaner yet - thanks for the hint

 

You could also buy (about $10), or borrow a NOID light for testing for fuel injector pulses. You just disconnect the injector plug and the NOID light plugs into the injector plug. The NOID light will flash to the pusles sent to the injector. If no flashes, then the injector will be getting injection pulses sent to it.