Getting Oil in the intake

My 1989 E34, with M20 motor, is passing oil into the intake and getting as far as the the air box. This current motor has about 180k on it. The car runs fine during the warmer months in NC, except for an occasional bucking in the morning when I have the a/c running. Winter time presents a totally different cenario. Hard starts, that's if it starts. with ether starting fluid. I don't think that I have a bad piston ring. I'm not sure if the oil in the intake is causing the bucking problem, but my thoughts are to fix the obvious problems first. The car seems to run too good for that type of situation to exist. If anyone has any ideas about my problem. I would certainly appreciate some assistance. Thanks in advance