your best bet engine wise (i would think, and this is what id do)

completely clean the engine bay - you can get a scrub on cleaner for this, just make sure the electrics are covered up

then you can get a thing from powercross (i think its called) that is said to clean the engine, you put it on the airfilter and it helps clean the carbon build up out

then id change all the fluids in it and replace anything that needs doing

should be easy enough to do and not tooooo expensive

should gain you some reliablity if not power increases