2000 Grand Marquis code po304
 

Code reads: cyl #4 misfire detected. I am going to pull #4 spark plug and check for any obvious problems with plug,wire, etc. Is there a way to test the coil or should i just replace it if i don't see an obvious problem with plug,wires? Thank you for your time, Chuck

If I'm not mistaken, your car has the coil on plug setup. A friend had this problem with his 01 Marquis a few years back. After two or three coils failed, he replaced all of them and never had another problem with misfires.