Toyota Repair: 1989 Toyota Corolla dieseling, fuel air mixture, toyota corolla

Question
My teenage daughter drives a 1989 Toyota Corolla.  She has had frequent problems with this car dieseling when she tries to shut it off.  We've given it a recent tuneup - new spark plugs, spark plug wires, rotor and cap, and replaced the oxygen sensor.  She's still having problems.  She claims this happens more frequently when the gas tank is full.

Answer
Hello Scott, welcome to my expert page.
Dieseling can be carburetor related or the engine is running too hot for some reason, if it's not overheating the carburetor is the problem, there is an anti-dieseling solenoid that is supposed to shut off the fuel/air mixture when the key is turned off, it's mounted on the carburetor, the condition could also be caused by carbon build up inside the combustion chamber, try using a higher octane gas to see if it helps, if it does it's engine related, if it doesn't help have the solenoid on the carburetor checked.