So I was driving down the highway and my engine started misfiring really badly. I scanned the codes, and it gave back P0300-P0303. According to the guy at Autozone, it's probably bad ignition coils. Is there a way to test the coils to see which ones are bad or if they are? I'd rather not replace them all if I don't have to. I have a ScanGuage II and a multimeter, and I could probably borrow some other tools if they would help me diagnose the issue. Thanks for the help.