90 voyager oil/distributor problem

I have a 90 voyager that i have had problems with. First Ill tell a little history. This van wa purchased about 5 months ago and it has a stalling problem where after about 15 minutes of running it will die and wont restart for 45-60 minutes if not longer. Well I just picked a good day to mess with it...lol...we have over a foot of snow and 1 inch an hour is still coming down here in upstate ny. my friend had a ford pickup that would stall if you stopped at a red light stop sign or whatever. He had to replace the distributor because the sensor in the distributor was bad but isnt replaceable without replacing the whole distributor. So i said why not try it. I have a part van so i figured i would give it a shot since it seemed straight forward. so i went out and got it off the parts van which was cake. I went to the good van and since it hasnt been started in 2 months had to jump it. so i start taking it apart and get the distributor cap and rotor and things off and i see oil in the distributor. Which I assume causes the stalling. Since the oil would mess up the reading of the sensor when its hot and once it cools off its fine. so i cleaned it all up and put in the sensor from the parts van and it started right up no problem and ran good for more than 15 minutes. I just went out to check on it and its dead but im not sure if its the battery that killed or the sensor because the lights dont come on so i need to jump it to get it started which im gonna be doing now. But could anyone elaborate on why the oil was in there and what caused it and what the fix may be. I am attaching 2 pics of the oil in the distributor.