My 1991 wrangler 6 cyl runs for few min then what appears to be exhaust and some oil comes out pvc and dipstick, whats wrong?

Sounds like a compression ring in one of your cylinders has broken and compression is being pushed into oil pan. Cylinder compression getting past the piston, instead of going out the exhaust it's going into oil pan and coming through engine (dipstick, air cleaner, PCV.) You'll need to have a compression test to confirm.