97 Jeep Wrangler issues - HEELLLP!

My jeep has three issues:
1- It is running hard and vibrating heavily when it nears 60 MPH while in two wheel drive. It can get so bad that sometimes I think it is going to die on me. When in 4 wheel drive, it runs a bit smoother and the vibrating is less pronounced.
2- My heating system is acting funky. The blower fan only activates in the highest setting, and no heat comes out; only cold air.
3- My gas dial is malfunctioning. When I fill the tank, it never reads beyond 2/3 of a tank.

Any feedback will be appreciated.