need some help

Hello I'm Edward and I recently bought this 98 Ranger. While driving around town, when I press in the clutch to downshift or to stop, the engine revs up real high without even on the throttle. (Probably 3500 4000 RPM) When I come to a stop or press the throttle the truck goes down to an idle...

I bought this to fix up and having problems need some help. The speed odometer and the gas gauge does not work. I finally got the steering fixed but am still working on it LOL. I also have a steering column for a 1995 in good shape it is used I bought it and I didnt fit.