The heat in my 2000 Cherokee has been so-so lately. Flushing it in the past has helped, and I know the previous owner wasn't too good with maintenance. This leads me to believe the core is plugged up again. Anyone know of a good flush to run through? I plan on just unhooking the heater hoses and flushing it back and forth with a garden hose. I saw the Prestone stuff at Autozone, wasn't sure if there is anything out there that works better.