I have a 1984 datsun/nissan 2WD standard cab/bed. it runs very good until it get warm or after driving it a while then it shutters and dies. I have done a visual inspection of the vaccum lines and they all look good. the PO rebuilt the engine at 170,000 miles and it has 187,000 miles on it now. could it be the fuel filter is cloged or the fuel pump is bad? is it the carb or is it a vaccum leak? I know fuel injected porsches but carbed inport cars are new to me. thanks.