When have you changed last time the fuel filter? Maybe the pump needs a hell of pump pressure to run the fuel through the filter. Could be also a possibility, although the pump itself could also be due for replacement.
As for the black colour in the tail pipes: also here you have to check the usual wear parts on your car which should be replaced in regular intervals, spark plugs, maybe the oxy sensor which gets tired after about 60K miles, and all the other wear parts in the intake system, including the airbox filter etc.