my neon stays running for about 5 seconds after i turn the key off.

 

i think you have hotspots inside the cylinder that keep it running, you could try new spark plugs. Another thing you could check for are leaking injectors.

 

can you explain what a hot spot is ?i was thinking ignition switch,,,,,,,,,,,,,,,,,,,,

 

hotspots can also be call pre-igintion or in your case run on or after run and is more common in diesel engine. Basicly its an ignition source other than the spark, such as hot spots in the combustion chamber, a spark plug that runs too hot for the application, or carbonaceous deposits in the combustion chamber heated to incandescence by previous engine combustion events.

The occurrence is rare in modern engines with throttle-body or electronic fuel injection, as the injectors will not be permitted to continue delivering fuel after the engine is shut off, and any occurrence may indicate the presence of a leaking (failed) injector.

 

I would check the ASD relay, swap it out with the horn relay and see if it makes a difference. The relay might be bad and getting hot, keeping power to the injectors and coil until it cools off.

 

i was thinking ignition switch???????????????????

 

The ignition switch is most likely your problem. Next time it doesnt immediatley turn off see if you can "jiggle" the key. If your car turns off it is the igntion switch. Pre-detonation is a little far fetched considering unless your running 12.5:1 pistons with 87 octane. I doubt that is the case though.

 

theres no such thing as Pre-detonation.

if the igition switch wasnt killing fuel and spark the engine would never stop. One way to prove you dont have run on would be by going outside with the car still cold, start it then shut it off while its still cold. If it still runs strong it could be the ignition cylinder.