Hi there, I recently bought a 1989 Itasca Sunflyer which was built on a Chevy P30 chassis, it has 60,000 miles. It has a Chevy 454 big block which started to 'diesel' whenever I shut it off, this would happen for about 15 or 20 seconds. I brought it to a mechanic who replaced spark plugs, wires, fuel filter, and cleaned out the carb. I drove it once since then and it was fine but then I had it idling in my driveway for a few minutes yesterday and after shutting it off it dieseled for about 2 seconds, I'm worried the problem will come back. Is this something I should be worried about? How can I fix this problem; I was thinking about running some 'seafoam' through the gas tank to clean out the fuel system, is this a good idea?

Thanks very much,

Mitch