Check for spark at the coil wire when the truck stops. Dakota and Ram pickups had a problem with the distributor pick up plate. I installed these on a constant basis as a technician in; Symptom is shut down when the engine is at full operating temperature, no spark, runs rich due to lack of proper spark.. The carb usually will cause black smoke from the tailpipe if too rich. When fueling this truck, stop when the pump clicks off... continuing to fill will cause the vapor lines to fill the charcoal canister with fuel, hence rupturing the canister and filling the carb bowl with charcoal..