My GREAT Explorer of 278K miles finally seems to have blown the head gasket. Last night I pulled into town after a 500 mile trip on the interstate, and it suddenly began sputtering and Check Engine light came on. It ran pretty normal above 3000 RPM, and Check Engine started blinking, but when slowing down the light went solid again and sputtering started back up. If it is the head gasket, what are my options for repairing/replacing? HELP please! I love this car! It gets 20 mpg on highway, but I won't chase good money after bad.