definately replace the fuel filters, this sounds like a fuel starvation problem. also check the tank screen, and all fuel lines for leaks. you may have an air leaking into your fuel lines which would cause the same problem.
another thing to check is the PCV system (positive crancase ventilation). if one of the lines for this clogs up or kinks, you will have serious problems with power, and could build up enough pressure in the crankcase to blow seals..
this seems like an easy fix problem. i don't want to get your hopes way up (just in case) but i'd start with the small, and most importantly, cheap fixes first.