2001 Focus PO304 code. Nothings worked!

Please go to this site, It will give full details on po304. God-Bless! www.obd-codes.com/po304

You have a misfire on cylinders 4-6 could be crankshaft sensor or signal coming from computer

THROTTLE POSITION SENSOR, MISFIRE, #4 MISFIRE, KNOCK SENSOR, THESE ARE YOUR TROUBLE CODES, PO120,PO300, PO304, PO325, RESPECTIVELY, REPLACE THE TPS @ THROTTLE BODY, REPLACE KNOCK SENSOR , @ ENGINE BLOCK, REPLACE YOUR SPARK PLUGS & PLUG WIRES ! AND YOU MUST ALSO REPLACE BOTH YOUR AIR & FUEL FILTERS, DISTRIBUTOR CAP & ROTOR , INSPECT, MAY NEED TO REPLACE, I WOULD ANYWAY !!!!!!!! ADD SOME GOOD FUEL INJECTOR CLEANER TO TANK, NEXT FUEL UP !

cylinder 4 misfire ,now if this is a GM product then i think you may need a reconditioned ECU init as if this is the 4 cyl engine and its same as the opel astra and zafiro and the vectra then its a common fault with a 2000 to 2004/5 model the computer is bolted to the engine inlet manifold and very weak and susceptable

This may help ??

Do you have spark at the number four cylinder? Check that if spark is present , then you should swap the injector from four to five and see if the miss goes with the injector. If not then you will need to test the engine compression .

ck if you have spark at the coil for that cylinder. check the plug wire closely. if it has spark at the coil, then replace all the spark plug wires.

I had this problem too exept I have no clue what parts or blah b;ah blah. I just know that my coil pack was getting fried.burnt out because my wires were bad. The mechanic I went to was a moron because I took the car to him 3 times and he kept saying it was the coil ad kept replacing it. I took it to my uncle and he said my wires were in horrible shape and when this is the problem it fries your coil making your car run like a lawn mower! Well all i did was replace my wires and the car ran great! Well I hope this helped..

I had the same car and the same problem.
My case I changed Air Intake
sensor(or call MAS), located right after air filter unit.
Good luck!

Out of the blue my light came on to. The code said was running to lean. I did a tune up. Found out it was well over due. New spark plugs and wires gave it much more power and runs smoother, they had been oxidized, fuel filter was needed also. Runs like new now. I did not realize my car was running so pore till i drove it after it had a tune up. Just a single mom's help hope it works.