What would cause my engine to run in reverse?

A bad ignition switch. If the engine was knocking and sounding really bad it could be dieseling,

Distributor wires to spark plugs could be crossed after a tune up. Check your firing order. The distributor cap could be bad and is missing some of its contacts or the cap is cracked. Replace cap. Distributor hold might have came loose and moved and now out of time. Check if loose. If loose re-time engine and tighting down distributor hold down. Broken spark plugs and worn out plug wires. Check and replace if needed. Fuel injectors wiring could have a short and causes it to flood the throttle body out just like a a bad carb float. Muilt meter needed for testing. Worn out cam shaft. Do a leak down test and compression test. Also worn out can bearing can do the same. Try these tips. If it turns out to be internal. Time to replace or rebuild engine.