95 probe gt problems

i just bought a used 95 ford probe gt
it has 110,000 miles on it
i was wondering if there is anything i should do to help improve gas mileage and increase power?
i changed plugs and airfilters today
when i was changing the plgs there was alot of oil ontop of them and i noticed my engine was low on oil
so also i was wondering if thats a damaged seal or something how do i fix it?

sounds like piston rings are way too worn or else damaged

it could also be the valve cover gasket. i had oil on my plugs, and found my gasket trashed. i have yet to find a way to increase power but get good gas mileage.. let me know if you find an answer. i have a magnaflow exhaust with a cold air intake, also my car runs rich which helps me with power. hope it helps.