I have a 2003 Buick
Century 3.1 L engine with 49K miles, has been running great until the other day, went to the store came home everything was fine, but when it was put into park it rev'ed slightly then started Idling very rough, and knocking..
I have replaced the EGR Valve, The Plenum Gasket, Plugs, wires, and all 3 Ign. coils.
I've checked vacuum hoses, fuses, and various connections.
I got rid of the EGR code but still have the P0300 code of Engine Misfire, any ideas what to check? keep in mind everything has been FINE up too when it was put into park the other day, and yes it has not moved since, still idling rough and knocking.....HELP!!! Rick Maxwell Goodyear, AZ.
Also there has been NO Overheating Issues, and Oil is Changed every 3K