After 5 minutes my Van stops working. I have changed the gas filter and checked (removed the fuel pump for inspection) everything is fine. A mechanic asked me to sit in the van and watch exactly what happens when the van dies. Here are my observations..... the van starts to slow down and sends out smoke out of the air filter and top of the engine and dies. When I go to restart it will briefly start and dies again immediately. When I wait a few hours it starts and runs like a new as if nothing is wrong. A few minutes later it stops running again and dies. Any ideas? Need help.