My Explorer has 130K miles and has been extremely reliable until recently. About 3 months ago, the check gauge light came on and it was the temp that triggered it. Fortunately, I was close to home. Took about 5 quarts of coolant to fill it. Nothing was wet. I replaced the thermostat about a year ago due to temp guage did not go above slightly warm signal, and that fixed the problem. Since the problem came about, I replaced the radiator cap. The heater core is not the issue. The oil is just what you would hope it would look like. There is a rough idle going on occassionally at stop lights. I did a coolant system pressure check and it stayed solid for over 20 minutes. Cap was also checked good. I never see the coolant, but I have lost large levels 3 times now. I suspect head gasket or intake gasket, but hoped it would come out in the pressure check. Something really odd is the vehicle can be off for a couple of hours or couple o f days and when I lift the pressure relief on the radiator cap, the recovery tank will burp almost violently enough to lift the cap off the tank. Any help is appreciated