Just bought an 88 bronco with a 351 in it. When it's cold it runs great except for a slight tick at around 2500 rpms.. As it warms up the oil pressure drops below the normal range at an idle and the red engine light comes on. As you accelerate the oil pressure comes up on the low end of the normal range but the tick starts around 1600 rpms and is a little louder. I've been told it could anything from an intake gasket to bearings to oil pump. I don't have a lot of time for trial and error so any help would be greatly appreciated.