Hey guys, I drive a 97 ford escort with the 2.0 sohc engine. For a long time I've had a rough idle and the rpms vary. The other night, it got MUCH worse and the engine shut off as I was backing out of a parking spot. I even feel some hesitation in the enging as I drive at cruising speeds. The check engine light came on and it showed a cylinder 4 missfire, code p304. Naturally I checked the plugs and wires and both were ok, I also did a compression test and that didn't show any problems. Any suggestions guys? I really wanna get to the bottom of this and get my car running strong again.

OK, you've got good compression. That leaves either...

1. Air/Fuel problem
Clogged injector?
Clogged Fuel filter? (probably get other cyls misfiring, too)

2. Spark problem
Spark plug? If they are the least bit old, I'd replace and gap (I think .054). I use the $1.29 Autolites in my 93 escort. Seem to work better than $4 Bosch platinum.

Plug wires? Did you check resistance? Observe for spark leak in total darkness with engine running? Good clean connection on plugs and coil pack? I use dielectric grease.

Ignition coil? You can test spark quality with an inline spark testor for $4 from Harbor Freight. You can pull coil and check for cracks in the epoxy.

It could be the Idle Air Control, too. It is on top of the throttle body with 2 8 mm bolts holding it in. It looks like a small elctric motor with a flange on the back. Take it out and oil it with a light machine oil such as 3 in 1 oil. You can spray it with some carburator cleaner. Let it dry then oil it. Don't let it soak in carb cleaner because some crud may come off and get caught in the valve.
Also, don't use any kind of lubricant with silicon in it. It will coat the 02 Oxygen sensor and cause bad fuel mileage.

Replace your plugs wires and put on a new coil. Had the same problem with my 99 (didn't get a light) and after a new coil all my problems went away!!!

couple years back i had a misfire problem
turned out it was the coil, wires and plugs all gone bad so id replace them all if i were you
also id go ahead and replace the fuel filter and look into checking the fuel flow at a shop
as for the iac i doubt it but i could be wrong
fuel injectors might be a culprit, it was for me, had a cracked one, but i had to remove the intake manifold to get at them i dont know how it is on the spi 2.0

the cap may have a hairline crack in it, replace the cap and rotor
i had the same problem

I had the same problem with mine. I changed the plugs, wires and coil pack. I also cleaned the IAC as Davescort mentioned. Had the code cleared and it came back almost immediately. Replaced the injector and that solved it.

These engines are notorious for dropping the valve seat and causing a constant misfire. it requires testing compression, if it's zero, and will not go up with oil, you either have a hole in the piston or a dropped valve seat.