bad intake gasket?
When you have a bad intake gasket or an intake vaccum leak you will have very poor brake response. If you have to pump your brakes to stop it's usually a sign of air in brakes or an intake vaccum leak. Also your A/F mixture will be wrong so ya it will run bad. Sometimes your intake will leak oil depending on where the leak is.
I've had an oil leak for a couple years, it used to be a few drips then this year it got bad so I had the rear main replaced since a shop told me that was the problem.. but it was the intake manifold 
so I'm doing it myself now, and cammin it while I'm in there. if you have an oil leak feel around the back of your engine above the trans(wish I did) if theres oil above the tranny its an intake manifold gasket, and if it is you should cam it while your in there too, maybe get some heads if you can afford them too 
and if it is your intake mani gasket this is a good read> http://www.geocities.com/MotorCity/Downs/4013/ol.html
so I'm doing it myself now, and cammin it while I'm in there. if you have an oil leak feel around the back of your engine above the trans(wish I did) if theres oil above the tranny its an intake manifold gasket, and if it is you should cam it while your in there too, maybe get some heads if you can afford them too and if it is your intake mani gasket this is a good read> http://www.geocities.com/MotorCity/Downs/4013/ol.html
