I HAVE A 89 GMC RALLY FULL SIZE VAN. WHEN IT IS PARKED AND RUNNING, IT IS TOTALLY FINE. AS SOON AS YOU TAKE IT FOR A RIDE SHE OVERHEATS. I HAVE CHECKED THE FLUIDS, AND THEY WERE ALL SET. NOW SHE HAS BEEN LEAKING ANTIFREEZE. THE ANTIFREEZE HAS ACTUALLY LEAKED INTO THE VAN ON THE PASSANGERS SIDE, AND SEEMS TO BE COMING OUT THE EXHAUST AS WELL. ANY IDEA WHAT MY PROBLEM IS?