1995 Ford Aerostar cranking but not starting

hi i have this van and its been a great van ......i shut it down and when to start it the next day and it wouldn't start but it trys to.... after a few days of playing with it i got it to run for a min or 2 but only with the gas peddel to the floor and it was not running good...... i have gas at the filter .....and spark at the plugs.....i now have oil coming out from the valve covers on both side (this wasn't happing before)....could it be as simple as a mass air flow sensor? or is it bigger?
thanks
nlarr