My 2001 Ford Taurus overheated on the highway. Got off the highway and turned car off. Car then would not start. 4 days later, car started sluggishly. Used a trailer to haul the car home. Now after 3 more days, car won't start again. It cranks but won't start. I am pretty sure it is the head gasket. Does this sound correct? Why won't the car start now?