P0300 new plugs,

Question

runs fine while driving, poor mileage. Stalls at lights, low idle 350-400, light black smoke from tail pipe. New plugs

Answer 1

P0300 Random misfire

P0446 Evaporative emission control system vent control circuit malfunction

Light black smoke , fuel being dumped into the engine, Beside fuel injector being checked, Make a inspection of the fuel pressure regulator. pull the vacuum hose connection, and see fuel comes out the regulator while the engine is running, If it does this would be the problem,