i get multiple cylinder misfire code on 1996 Buick Riviera

checked all plugs, wires and coil packs they are fine, O2 sensors and mass air flow sensor are also new as well as fuel filter. now it is smiking bad from exhaust, and oil drips from mufflers, rough idle revs and stalls

Get Your Car Fixed at a RepairPal Certified Shop.
We certify shops based on expertise, quality work, and verified customer reviews
1 answer
possible intake gasket leak, fuel pressure regulator, or ignition module