ok so last night i started my car up and it idled fine but when i engaged the clutch it made a screeching noise and my rpms dropped below 500 and my headlights dimmed, the cel came on and it almost died. when i was driving everytime i shifted it would screech my rpms would drop way more than they should and i could hear it pop from backfiring. my headlights dimmed too. i figured that the pop was from the rpms dropping too much and having all the unburnt fuel. i just am not sure what could cause all of this to go on. thanks.