I'm practicing for about 2.5 years now, last year using TMI book. I've (most likely) had A&P experience around Jan'17 doing 'close following' practice. There was some turbulence in my practice afterwards and I was feeling socially awkward a lot. It lasted for about two months. Then I've reached effortlessness (as per Stage 7 description) and everything was fine again.
Sadly due some lifetime events my practice degraded and all this turbulence came back. It repeated 2 times at least. So I've decided to focus more on this 'close following' (it resembles noting practice I think) paying attention to three characteristics etc. After some practice I feel fine once again but I'm not sure if that's equanimity nana (as per MCTB ).
These days my meditation goes like this: after initial preparations (four step transition, counting breaths, focusing) I gradually speed up and spend some 10-30 minutes with rather harsh vibrations (frequency changes all the time, 5-10 Hz, my body shakes a lot during this time). Afterwards frequency slows down (like 3-4 Hz) and becomes more rhythmic. I can follow sensations from beginning to end. Vibrations spread through whole body, but slightly out of sync. Some shaking remains but not so erratic. It is quite effortless and frequency sometimes goes up and down all on its own.
That's it. Any input would be appreciated.

Hello, welcome!

It sounds like it could be late dukkha nanas / low equanimity. For me, the key to transitioning to high equanimity is:


Pay attention to the "out of sync" quality of vibrations in different sensory channels. The transition to hi-eq, for me, is about those vibrations synchronising. Once that happens, try to drop effort like Culadasa explains in stage 8.

Thank you! I do feel some unsatisfactorness in this 'out of sync' quality 

Good. Don't force it though, it should happen on its own. Let us know how it goes.

Last week or so new pattern has emerged. After all previous steps if I go to choiceless attention like state body perception becomes hazy and tingling. It can slowly twist, contract and sway, especially when attention moves on body. Those effects are different from TMI choiceless attention for me. If I direct attention to this tingling in body volume it becomes more pronounced, like moving back and forth very fast.