Volvo Repair: 760 GL Turbo runs rich no power, fuel pressure regulator, turbo intercooler

Question
Bilbo, I just bought a 87' 760 Gl 4 cyl with turbo intercooler, 160,000 miles. Picked it up in Carolina Beach drove back 6 hours to the mountains where I live. No problems at highway speeds but performance started to detriorate on hills. Now it will not pull the smallest incline. Above 3000rpm the motor catches and it runs fine, when it dropes to 2500 rpm or less no power and black exhaust as if it's running to rich, also gas consumption drops to single digets. Have replaced the fuel pressure regulator, no change. I have modest mechanical skills but have a good friend with extensive knowledge and skill on the 240 models. Any help with this would be great, I really don't want to replace the works when it may be as simple as a cracked hose, thanks for your input-bbqbob  

Answer
Hello Bob,
         My advice is...change fuel filter...test the Air Mass Meter...here's how...locate it...and with tender care remove wiring connector...start car...if it runs better..you need a A M M.
         
         Have dealer read problem code.
             
          Good luck,

             Bilbo