I have a 2000 Saturn Sl2 and it has around 190,000 on it. I drove it to work one morning and it ran fine. When I got out of work it had no power when accelerating and when checked diagnostics code it gave me the P0300 code of random misfire. I changed plugs,wires and coil packs with no fix. I went and got a new fuel filter and replaced it and it did fix the problem for a solid day before it went back to the same issues. Any advices would be appreciated.

 

1) What kind of plugs did you put in?
Stick with the NGK copper plugs OEM.
NGK 5643.

Single most common reason for misfires in this engine.

I know it was an issue before the plug change but I can't turn back time so let's work forwards.
What was in there?

2)How much oil do you burn / 3,000 MI?

You are near that mileage when the valve guide seals tend to let loose if they haven't already.
You then end up with oil fouled plugs and misfires because of it.

3) does the car feel like it is running on all four cylinders or is it firing unevenly?

4) given mileage and wear, compression may be coming in to play.

Pull these plugs and check for oil fouling. If significant, do loan a tool from AutoZone or similar for a compression tester and test the compression in each cylinder while you have all of the plugs out. Remember to hold the gas pedal all the way down while cranking during the compression test (wide open throttle). Perform at engine operating temperature. After initial check, put a small amount of oil into the cylinder and recheck. Capture both values.

Report oil fouling and compression results here and we will take it from there.

The NGK spark plugs are somewhere between $4 and $6 for all four.