Why do 2001 Pontiac firebird engine won't turn off in the off position?
You probably have after-ignition, usually caused by operating
with dirty fuel. The way a mechanic explained it to me is that
there is (very small) debris in the cylinder, on the piston. When
you hav edriven enough that the engine gets to a good tempertature
and turn the engine off, the debris (if it's large enough) is red
hot and causes any small amount of fuel to ignite, thus causing the
piston to go down, thus causing more gas to come in to the next
piston ready to fire, debris is hot, and it just goes on and on.
Seek the advice of a knowledgeable mechanic or get Chilton's
mechanic repair book and check the trouble-shooting section. In
short, my opinion? bad gas, my friend. Change gas stations.