First Long Trip in My 420SEL

I just took a 360 mile trip (each way) in my 1986 way up north of NYC near Canada for Thanksgiving. (1) It was cold, my gauge read a solid 70 all the way and cold air came from the vents except at a stop or slower speeds. (2) The car was not quick going up hills, the tach was only reading 21,000 rpms and would not go faster than 40-50mph! and (3)The scariest thing was the cruise control seamed to get stuck in accel and would not disengage by braking or decel on the wand, I had a small panic attack, put it in neutral, the tach flipped and in finally disengaged (whew). Any similar experiences? solutions?

Thanks