When first started, car runs rough, shaking and mis-firing. Check engine light comes on. After driving for a while, it fixes itself (light goes out, all is well). Full tune-up has been done, plugs wires replaced, code check says one cylinder has mis-fired but problem only occurs intermitently. Could this be poor gas quality? Bg44K fix? Emission valve? What?
My first thought is a carbon issue on an intake valve. Common issue for cold start miss fires. An intake cleaning would hopefully take care of it before talking a valve job.
The other issue may be an injector with a spray pattern issue.
At any rate, you need someone familiar with these problems to verify the failure and lead you in the right direction.
October, 9, 2011 AT 4:02 AM
Valve clearance adjustment might solve the problem if they are the cause.
If the idling speed is too low, it would also cause the misfiring and rough running. The cold start system might not be working correctly. Have the throttle body, IAC and thermo valve cleaned and retest.