1983 300D Automatic Transmission Trouble
 

My 300D (turbo) is having trouble shifting. When it should shift smoothly into gear (usually between 2nd and 3rd or 3rd and 4th), it jerks like it is trying to shift into gear but can't. It's hard to describe, but the car visibly lurches during shifting. Eventually, the car will shift into gear, but it sometimes takes a while.

Anyone have any ideas of what we could try?

Check to see how much vacuum is getting to the modulator. Hook up a vac gauge to the line going down to it from the top of the VCV.
Too much vacuum will result in the shifting problem you describe.

Thanks for that suggestion- I will obtain a vacuum gauge and try that.