87 300D climate control and hard shift trouble?

[dalpil]

Hi, been doing alot of reading and now it's time to just ask. I bought my wife a sweet '87 300D last May. This fall I noticed the transmission starting to upshift hard - almost like it has a shift kit installed. Wasn't that way when we bought it. Now that winter has set in (we're on the shore of Lake Erie in Pa) when we get in the car in the morning the climate control blasts full heat for about 10 minutes or so - no matter where the controls are set - and then can be manipulated like they should. We regulate temperature by selecting the low fan speed. The air seems to come out of the vents it should - although my wife says there's no heat on the floor. She drives the car alot more than I do. Lately I've noticed that the temp settings are behaving better than they did last month, and sometimes the hard shifting disappears.
Kind of thinking a vacuum problem but don't know where to start. At one point thought replacing the temp control was the way to go, then learned the hard shifting is vacuum related and tied in with the climate problem. Hoping it isn't the all day pod replacement where the dash comes out and all that. Please tell me that isn't so. Any help offered my wife would really appreciate.