all you have described I have experienced, and it has been due to a few different problems, one which is invisible and easy to fix, and the other which is visible and not so easy to fix.
The easy one to fix has been surface contamination, oils like suntan oil, transfering from hands to mast and wings or spf oils on hair transfering to the mast when carrying the board mast combo to the water with the mast resting on my shoulder, and the worst one is the tefgell grease used on the screws getting smeared on the wing surfaces and "removed" with a quick wipe,
try - spray glass cleaner, or a cloth rinsed in hot water and washing up liquid, work into the surfaces, all areas and edges.
then polish dry with a microfiber cloth that's very clean and dry, or new kitchen roll paper.
And then to confirm if you have a contamination issue, run tap water over the surfaces, and look for a complete mirror sheen of water, no breaks in water grip on the surfaces, anywhere, for at least 5 seconds, re-clean any areas where the water avoids, and re-test.
for fun just press a finger on your mast surface, then run water over the area, the water just avoids your finger print, and that's a problem right there, imagine a full hand print and the havoc it plays as you build a little speed through the water.
the other problem that can cause the wobbles is a mast leading edge that's not that smooth and this goes for all leading edges on your wings, I did forget to maintain my carbon mast leading edge, and on very close inspection it had all sorts of imperfections, air holes and rough feeling areas, not the best.
to cure this was a bigger job than I expected, and involved a trawl through the words of wisdom given by the guys who make mike labs race foils,
west system epoxy was brushed on the pre-prepped full leading edge, masking tape was applied along the full length around 3cm down from the front edge, when dry
the full front edge area was fine finished with 800wet/dry paper, then 1200, then 2000 paper, this wet dry paper process took some time as the lip of new epoxy had to be perfectly feathered into the masts main body, which was a labour of love job, a 101 mast is long and has two sides,
but a few hours later the mast was ready for the magic finishing that until reading the mike lab "how to maintain your mast" advice, I knew nothing about,
off ebay I bought finishing pads of 3000 grit and 4000 grit, these are 3M quality or similar, round 6 inch, thin foam backed dry use fine finishing discs, they are the secret tool to maintaining a super smooth edge and finish to your mast edge and wing edges, the finish you get is so fine and polished, so much better than any one way finish you can get with wet/dry paper. these pads are only around £3 each and last ages
https://www.ebay.co.uk/itm/Mirka-Abralo ... 4902.l9144