What can I do to improve my 97 Mercury Cougar?

Thinking of several different things. I want to put in a bigger engine, but with gas prices don't want to. So I was wondering if there is a V8 out there that will fit in my Cougar with little to no problems and has the valve shut off option for when all 8 cylinders aren't needed or wanted. I also was thinking of getting it raised a few inches (so that I can fit all terrain tires on it because I go down rough dirt roads) but don't know the best way to do it. Any suggestions, facts, or sources are greatly appreciated.