I am having that same problem. When I first got my truck, it would sit there and idle for 10-15 minutes. After about half a gallon, I cannot start the engine unless I give it some gas while cranking it. Once cranked though, it will idle for at least 5-10 seconds until it cuts off. I tried to start it yesterday and my stupid roto start battery died because it took so long to crank it.

I guess I'll start at the factory settings and see what happens.