This has been happening quite often. As soon as the gas cap is removed, the motor dies. It's always low on fuel, that's why it comes off. When I crank it to restart, it wants some throttle before it catches and starts. I checked with my Dodge mechanics, and they had never heard of this. Any guesses?

 

Your Dodge mechanics are correct. Never heard of it.

 

I could make a wild guess....

That year gas cap is non vented...the vent is to the charcoal cannister. You have a hole in the pickup tube in the tank. The charcoal vent is clogged so when the gas cap is on there's enough vacuum in the tank that fuel still gets sucked in through the hole....remove the cap you've introduced a big vent and now you're sucking air instead of fuel through the hole. Only thing I can think of.