This is caused by poor conversion from the original NTSC sources to the PAL versions.
Or at least, that's usually the situation.
Were these native PAL sources? (Not common.)
Or was this an NTSC broadcast, film, etc -- that was later converted to PAL for distribution. (Most common.)
Many, many, MANY, official VHS releases are like this. The interlacing is messed up, as the work was budget grade -- sometimes even done on consumer quality gear (consumer off-the-shelf VCRs, not pro recording VTRs).
Ghosting is sometimes cured with srestore() in Avisynth.
Choppiness can almost be irreversible, depending on how many generations of signal conversion caused the problem.
If you mess up interlace, and then re-interlace it again, that can be beyond repair. Moreso if any resizing was involved. In these situations, I've found that sometimes you can load the video in
VirtualDub, run Yadif deinterlace, then directly beneath it run a Deinterlace Area-Based filter. I did that just 3-4 days ago for a small clip. It worked. The Area-Based filter doesn't concern itself with interlacing exactly, but targets instead the combing artifacts. It can attempt to restore progressiveness with a true decomb, but the better choice can the blend the mess on bad recordings. Area-Based has both options. Try both, see what works.
One thing I've not yet tried is to run srestore() after the area-based decomber, when it was set to blend. That may be a fun experiment.
Not sure if any of these methods apply to you videos, however. To some degree, that almost sounds like more of a codec error, or a file corruption issue. I recently opened up some files that I made back in 1999 or 2000, using an early version of MPEG-4 encoding (Divx version 3, maybe?) and I could not find anything that would play it without skipping all over the place. What you describe for your videos actually sounds pretty close to what I saw then.