If you want a car that sprints from stoplight to stoplight and cruises at 80+ mph you will not be happy with the NA diesel 300. Power comes with RPM, it takes a different driving style. This is NOT a performance oriented car.

Any way that you cut it you are talking about a car that is over a quarter of a century old and if you are not equipped to deal with that you will not be happy. People sell cars when they are four years old because they are old cars.

Modifying a car for performance is an expensive and time consuming proposition. Keeping a 25 year old car serviceable is an expensive and time consuming proposition. If you want to do both and don't have deep pockets and plenty of spare time you are probably not on the right track.