I have found that if i spray carb cleaner around the back of carb when running it will kill the motor around back i mean behind the carb between the firewall and carb body I have tried to track down the leak but cant find where the problem is ????? also how do you tell if your dist parts are worn or failing ??? thanks Frank 1986 f150 4x4

 

Make sure your carb isn't loose causing a vacuum leak underneath. Mine has a tendancy to do this over time.