well i know that you can program the pcm for power but is there a way to tune for higher mpg'*?

You can adjust the timing in the cruise areas, and lean out the AFR a bit in that area as well.

do you think that would make much of a difference?

A huge difference if you'd like. Tuning basically lets you do whatever you want. If you want to run with almost no gas at all, supposing your engine can run that way, you can do it by tuning. But your car would be so slow. So very slow. Your 93 SSE should already get about 30 mpg, though.