85 240DL Auto 206,000

Here's the deal. Engine suddenly began running rough some time ago. About every 1-2 seconds the the engine cuts out as if it is missing. However, the power seems to be fine, i.e., if it weren't for the brief but persistent cut outs, the car would have plenty of pep.

Some other symptoms that may or may not be related:
1) Funny smell from the exhaust - had the cat replaced a few months ago. Smell seems to be coming from where the cat is located.
2) Recently the car will slip out of gear (automatic) for about 5 seconds when starting out cold. Once it slips back into gear, it seems to be fine after driving a block.
3) On occasion, the rough running will disappear for awhile (5-10 miles). No rhyme or reason as to when this happens - warm or cold.
4) The engine will die sometimes when it is cold - but not often.

I've had the AMM replaced a couple years ago and this doesn't seem to be an AMM problem. Disconnected it once and there was no change to the engine at idle - warm or cold.

The transmission problem is what throws me. Could this be a vacuum problem? My mechanic was too busy to work on my car said to check the oxygen sensor connection. It looked ok (if I was looking at the right connection).

Thanks in advance.
Dean