I have a 1985 mercury marque,302 throttle body carb?

that 302 is famous for jumping a tooth when it gets a lot of miles on it. go buy a new timing chain set up and put a new one on. I had almost every 302 I owned do this, it fires up one last time and hits on tow cylinders and dies. its hard to figure out because the rotor turns when you take off the cap. Do the timing chain and get the marks right. If by chance you had problems with the any time in the recent past, it stretches the timing chain and it will jump a tooth best of luck