2001 Dodge Caravan vacuum leak message

First thign would be to tighten the gas cap and reest the code and see if it comes back, also check the gasket on the cap could be faulty.

The best way to check for vaccum leaks is with a can of carburator cleaner and the vehicle running, if you find the leak the engines idle will go up.

Caravans have some interesting areas that can create those codes. The only way to really test the system is with a smoke machine. A failed gas cap, gas tank fill pipe, vacuum lines from the tank forward the leak pump attached to the front cradle. Plus a few other vacuum lines. Use a smoke machine and it should take about an hour. Do it the hard way and take a day or two.