New owner of a 01 tiburon, having problems.
 

Hey I just purchased a 2001 tiburon (automatic). I've been having nothing but problems with it so far.. I already got a transmission seal fixed and still have to get another transmission leak fixed. I filled my tank a few days ago when I first bought it and I only have a quarter tank left and I only went 170 miles, someone told me it might be because of my air filter so I got that changed but I don't think that would make my gas mileage that awful. There is no gas leak either. When I go over 60 mph the steering wheel vibrates pretty bad and sometimes when I'm driving my transmission won't shift at all, but when I turn my car off and back on the transmission will shift perfectly. Also is it normal that my car heats up really fast?