I let one of my mb mechanic friends talk me into letting him take the heads off. He was convinced that I had worn valve stem seals....

Well the machinist said the heads were beautiful and that the seals were fine, but I replaced them anyway..While I was there, new motor mounts, and new plugs, wires, (ouch!)...Still smokes like a pig after about 30 minutes.... Guess I threw parts (and time and $$) at something...Anyway, still scratching my head... Any additional ideas?

After smoking, I can shut the car down, let it sit 30 minutes, and then it idles runs/without smoke.

I checked the cats to see if they were causing pressure in the crankcase via backpressure, and they weren't...(zero backpressure at the beginning of the cat).