i have and 84 gt w/ a ready to run distributor. i am having problems shutting down the engine once it fires. the key wont turn it off. i have to shut the choke by hand to shut it down. when the engine is running i have 14.4 volts on the positive side of the coil and 12.1 on the negative side. i have a resisted wire filter on the negative side which i had sent to me from MSD. doesn't 12 volts seem high and could that keep the engine running. or coud it be an ignition switch? also after it runs for about 5 mins. it just dies. it starts right back up but dies again quickly.