Codes P0300, p0303, p0420 pop up idles rough plugs changed fuses checked

Hello, sounds like you're experiencing an engine misfire, and what's worse - continued driving with a misfiring engine can damage the catalytic converter -- which by the P0420 code being set may already have occurred. It's not for sure, though, so best to resolve the engine performance concern before diving into anything else. Misfiring can indeed be caused by spark plug issues, but can also be caused by a faulty ignition coil (in this case, depending on the engine your vehicle is equipped with - it is likely a single coil with 4 spark plug boots - which is where the failure may be occurring). It can also be caused by an internal engine concern, such as valve train or base engine issues. Hands on testing is needed to determine what needs to be done. It's not enough to just replace spark plugs - when the problem may be something different. https://repairpal.com/auto-repair-near-me Click the link or call us at 877-913-1554. We'll gladly find you a certified RepairPal shop in your area.