check engine light, p303 code

I'm pulling up a p303 code right now, says cynlinder 3 is misfiring, anyone know what this coiuld be? think it said it could be a vac leak, ignition, fuel injectors....but want ti see if anyone else has gotten it before.

I used to just reset and clear that if it came up. When is the last time you changed the plugs? If it comes back this is what it says at OBD-II site:



If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

Try this. i had a code come on today, po301. Cyl # 1 misfire. Make sure your coils are ok.

Remove the ignition coil.


A. First pic




Measure the resistance from lead hole 1 to 4, and lead hole 2 to 3 using an ohmmeter.
If not as specified, replace the ignition coil.
Specification:
ZM 8.0 - 12.0 kOhms
FS 7.2 - 10.8 kOhms

Insulation Resistance of Case


Disconnect the high-tension lead.
Disconnect the ignition coil connector.



B. Second pic.



Measure the insulation resistance from terminal 1A to ignition coil case, and terminal 2A to ignition coil case using an ohmmeter.
If not as specified, replace the ignition coil.
Specification: Above 10 MOhms

ok so my cel disappeaered again. I'm started to think it has soemthing to do with my egr vavle, it's lose but hard as hell to get to with the thread lock and manifold in the way. oh well, does'nht seem to affect driveability at all, so i'll see what goes on, still planning on chnaging plugs and coils and everything thoguh as general maintence

First, replacing the coils isn't a general mainteance thing, only replace those if you are positve they are bad and are the cause of the misfire. Second the EGR is lose on the Intake mani, or on the exhaust manifold?? and if the EGR were to be loose in some way it would affect drive-ability and idle issues. Check compression, spark, fuel, and air.

i do have idle issues but no drivability issues, i did have issues, but fixed them