We have a older forklift it will start and run for about 10 minutes then die then it will run about 30 seconds die start die until it sits then it will run 10 minutes and die. It will run on gas not real good it hasnt been on gas in years. It has a vacuum LP valve that is working and the converter is new. I put a low presser gauge on the converter and it has presser even after it dies. Its also fireing the plugs after it dies. I have worked on alot of LP engines but never had this problem.