sounds like it could be just a bad ign. switch remember you turn the switch on and one of the thins it does is turn on the power to the distributer if when you turn the switch and it does not cut off the power then the eng. stays running ......i would start there in that system any way do wiggle test on all the wires to make sure no loose connections and or breaks....hope you figure it out

 

first try Slowing the idle down. The knowledge base is full of posts on this problem.

Troy

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Stop

Doc hereimp:

Is the car dieseling or Just not responding to shutting off and idling normal on "OFF"?

If it's not dieseling, then check your secondary Ignition wire to be sure it's not staying hot after you shut it off..It should be on the "R" side of the Solenoid, not the main terminal link wire...This is a common miswire when changing starters ETC..

Check to see you Don't have 12 volts on the coil when off...If so, find the source and remove it.

Next would be a bad switch.

Doc imp: