The other day I heard a pop and I checked my engine and noticed the spark plug wire from the 4th plug blew off, i put it back on as my car was running and it shook then popped off again. even with it popped off still touching the plug my car ran fine. I checked the plugs and that plug was pretty black. I changed the plugs to the stock ones i had in my car. my car seemed to run fine and the wire stayed on but got a screeching sound at high rpms. This morning my car wouldnt stay running, idling extremely low and sputtering, i changed back to my stock wires and now when i start my car its idling at 2000rpm and i get a loud screeching like metal scraping metal if i give it gas past the 2000rpm. Any ideas?