I have been to 3 shop and spent alot of time and money and no one can fix my car. It will misfire and show a code( po300-304 ) at cold start. after it warm some it runs great. We have replaced all plugs ,coil packs ,check for vaccum leaks .From what i can tell from different forum post this has happened to others. But I never see an answer to the promblem.Trust me we have done it all but remove the head.There has to be an simple reason it does this .HELP!!