trouble with 95 mercury villager

hello I am writing cuz I own a 98 MERCURY VILLAGER van and am experiencing a prob.

My engine light turns on after driving 10 mins then turns off after like 15 mins.

I do often experience a problem with "pickup"

some time It picks up and goes great ,...butwhen accelarating to 60 mph on freeway,...it drags. sometimes I hear a rough sounding noise and feel heavy grinding vibrations through the gas pedal.....was told it could bemy fuel system .any thoughts?

I bpught this used from an auto dealer.But they claim to not know the history of problems with the vehicles they sell,...only that they will pass state inspections.