Truck will start up no problem, if I place in drive or reverse, shut off.

 

Need to give us more than that.....read this so you know what we expect if you come here for assistance....

https://dodgeforum.com/forum/3rd-gen...our-visit.html

 

could be a seized torque converter. stator seized within. or a vacuum leak. or any of a couple of more things I can think of. 87 would be carb'd, could be issue within. if its in good shape for the year I would fix it but that is me..... (I do all my own work so I don't have to pay a shop labor fees)