Re: 350 stock engine
Bet you have a lumpy rumpity-rump cam also. I will also wager that you have your throttle blades half way across your carbs transition slots (making for carb hesitation on take off) because of that cam.
The throttle plates being set too far open is allowing air and fuel to enter your engine and a very high static compression ratio is converting your car from the Otto cycle to a very inefficient Diesel cycle when you turn off the key.
Dieseling isn't a plug problem, but a carb problem.