Originally Posted by L33T Z34

P0300 means multiple cylinder misfires. The OEM FSM lists the following possible causes: improper spark plug, insufficient compression, incorrect fuel pressure, fuel injector circuit open or shorted, fuel injector failure, intake air leak, ignition signal circuit is open or shorted, lack of fuel, signal plate, A/F sensors damage/short, incorrect PCV hose connection.

My top guesses would be he damaged the crank position sensor (signal plate) OR fuct up one or both of the A/F ratio sensors. Least likey would be insufficient compression, improper spark plugs, fuel injectors, fuel pressure, PCV hoses.