I need some help solving my misfire problem. I recently change the spark plugs and wires airfilter and fuel filter. Now i am having random misfires and my car is running rough. The misfires happens when i accelerate at speeds of 45 and up. Can anyone please help.

 

Considering the recent repairs, I am going to go with incorrectly gapped plugs. I would pull them (PITA I know...) and regap them. You should be good after that. Also, if it hasn't happened yet, you will get a flashing CEL that reads 'random intermittent misfire'. Good luck!

 

If the plugs are BOSCH, throw them out, put AC Delcos in or even NGKs. BOSCH are crap.

How does the car idle, how does it rev? Check to ensure you did not brake or loosen any vacuum lines. If it's idling bad from the get-go, ensure firing order is correct. Make sure the plug wires are not in contact with anything hot (like exhaust), and that none of them are damaged (damaged wires could lead to arcing).

Miller also has a good point about checking your gap on the plugs. All the AC Delco plugs I have work with were almost pre-gapped dead on, but they should STILL be verified.

 

Fueling issues can also cause a p0300 (random misfire)

Fuel Filter could be clogging and not allowing enough fuel for the car?