I just went out to my car tonight and it's idling rough and when I accelerate it seems like it wants to stall and the check engine light came on. About a month ago the check engine light came on and the code read cylinder 3 misfire but the car was running with no problems at the time. It has new plugs, wires, and fuel filter in the last 6 months so what can I do to diagnose the problem on my own?