ENGINE LIGHT
THE LIGHT CAME ON HAD IT CECKED SAID CYLINDER 4 NOT FIRING HAD SPARK PLUGS AND WIRING AND AI FILTER CHANGED, LIGHT WENT OUT AND CAME BACK ON, HAD THE CYLINDER REPLACED STILL MISSING A LITTLE, REPLACED OLD CYLINDER BACK ON. ENGINE LIGHT WAS BLINKING AND THEN STAYING ON STUDY, NOW IT IS STAYING ON STEADY. WHAT COULD BE THE PROBLEM AND HOW DO IT GET IT FIXED PLEASE I BOUGHT THE CAR IN 2009 USED AND HOW MUCH MIGHT THIS COST?