My stock hatchback runs very well and will not miss a beat all day long in the Las Vegas heat. Having replaced nearly the entire system. the a/c is in excellent condition. Problem is I can't have both running at the same time or she'll die after a few miles. After that she'll turn over but won't start, then about an hour later she'll start right up like nothing happened. Some symptons before it happens are wildly fluctuating rpms, loud valve knocking, power loss and such. Any thoughts out there will be most appreciated.