273 intake on a 318

car ran fine the day before i switched intake, i pulled the plugs out and they were a little black but they didnt smell like gas at all. the ignition system is new. is there a chance of a blockage or gasket slip, or carb jets not putting out enough gas on that side to feed all cylinders? sprayed starting fluid around intake, found no vacuum leaks. could i have fowled the plugs? not looking forward to pulling intake back off.