I was driving on the freeway today when I noticed the temp gauge rising fast. As soon as we hit an uphill, it quickly got into the red and I pulled over and popped the hood. After sitting for like 15 minutes, the coolant in the overflow bottle was drained all the way to the bottom. I didn't have any tools with me so I refilled with coolant/water with the engine running and heat all the way on. I made sure there were no pockets left but the car still slowly was creeping up on the temp gauge and I barely made it home. I had to pull over a couple times to let the engine cool down. The fan was definately working and i'm pretty sure there are no air pockets left in the cooling system. Does this sound like a bad thermostat? This was on the 96 Mark VIII, all stock, 66k miles on it.