I have a 1973 plymouth duster inline 6 225, it's completely tuned up the engine got rebuilt a few year back, not too any miles on it cause I joined the marine corps, I started driving it and now after I drive for a while or on the freeway for a log distance, when I slow down it keeps trying to die and ussually does, when I try to start it the starter sounds differnt and it runs horrible till it cools down, please help

 

Check the electrical/ Charging system and the starter

 

Also Check the fuel Pressure and make be the float level needs to be reset?

Also...Welcome to the site... and Thank You for your services and protection....

 

Does it have a temp gauge? How hot is it getting?