hey guy's , i wonder if any of you can shed some light on the slight problem im having . ok about 3 days ago my car was very difficult to start when it was cold but once warmed up was great at starting & idling . yesterday i put new spark plugs in which solved the cold start problem but now whilst my engine is warming up from cold it sounds like its missing slightly then once its warm its fine with no misfire at all . what could this be ?? oh & ive already disconnected the cold start valve but it hasnt made any difference so it isnt that .