It sounds exactly like the intermitant problem I had on the auto trans in my 84 240 earlier this fall. I have been unable to diagnose its source. Many people suggested that it was low fluid, but that was not it. The fluid was purged and the trans was refilled with new; the filter was cleaned. The fluid level is correct. The car still has the same problem.
One thing I noted was that it was only when the car had been sitting overnight or for an extended period, although it was not necessarily repeated each time those circumstances occurred. As I said, intermittant.
If it is any consolation, the problem does seem to be less frequent now than it did a month ago. This could be attributable to air in the system from the oil change which has now worked its way out, or colder temperatures now when starting. I hope the problem does not return. Sorry I don't have any suggestions for your relief, only encouragement to hang in there.
JD