code 556: vacuum leak, EGR or fuel pump?
after replacing my IAC, PFE and EGR Vacuum ergulator, I cant figure out why I now have part throttle stumble. It feels like a vac leak; but the codes say Fuel pump primary circuit failure. I've checked the vac lines and dont hear or see a leak. The Throttle body "elbow" was removed and cleaned as well.
Under load (uphill) the car stumbles with a rough idle until I hit the passing gear, Then it seems better; but still underpowered.
anyone have an idea of what I want to try next?
92 merc Grand Marq. 4.6