Got p0171,p0174,p0300,p0304,p0307,p0308 have reason to believe my intake has to come back off! Used enrichment but could not see a short term adjustment.
Just replaced intake gaskets ran great for a week now misfiring on 1999 Lincoln Navigator
Sounds like you have a big intake leak causing the engine to run lean, misfire and set the codes. if you can't find a leak anywhere else, you may have to remove the intake and check your gaskets, etc.