"Sawing" engine on slow speeds 207d

[Huckleberry]

I recently purchased a 207d campervan , it was imported to canada from germany. It is 1980 in decent shape. When i drive at slow speeds (0 -1500 rpms approx) in 1st and 2nd the van saws. Kind of a front to back rocking. I checked the vacuum line on the throttle with mity (as well as cleaned out the air intake) and the line was leak free. There seem to be no problems with accelerator all the way down. Is this a sign of the vacuum pump diaphragm is worn? or does someone have other ideas.

Second question, the blower motor doesn't work, are these the same motors that are in the 240 sedans of the same era? are the brushes easily replaceable?

thanks kevin