runs a while then dies has no spark
 

Hi everyone I'm new to this forum and i need some help!!!!!

I have a 1990 B2600i pickup 4x4, many things have been replaced on it including 3 engines...It will start and run for a while, but when it dies it will not start up again for at least 2 hours and has no spark at the spark plug wires....also it smells like gasoline at the exhaust, Coil, distributor,fuel pump, computer, ignition switch all have been replaced. I sure could use some help to get my little truck running again...Thanks