1988 Ford Escort Battery

Engine Mechanical problem
1988 Ford Escort 4 cyl Two Wheel Drive 150090 miles

My car has been running great. Today I cranked it went about four miles turned it off. About an hour later went to crank it and the battery was slugish. It cranked. I drive it 12 miles turned it off and it would not crank, dead. Pushed it off it cranked right up but all the way home the engine surged every seven seconds. The speedometer didn't work the turn lights, the horn and the gas indicator didn't work. Going up a hill it was too weak to make it it went dead. When we hooked jumper cables to it it cranked right up without the other vehicle even being cranked but once we removed the jumper cables the coolant fan would start to engage and it would go dead. What could be pulling the battery down?