I am always amazed at what a simple trans fluid change will cure. I had a similar issue to yours with my 240D trans slipping and not staying in gear and I changed the fluid and filter and it seems to be operating better now. Still not right but better anyway. My transmission is one of the old non vacuum units so there are many more variables involved with yours.

Stretch is correct about the transmission needing to be at operating temperature to get the correct readings with the gauges. Hopefully it will be warmer this weekend so it should be easier to get the car warmed up.