I play microstakes, have 200k hands and am doing pretty okay (not a full-time player so I'm satisfied with my EVbb)
I'd like to ask you good folk for some mindset advice, would really appreciate it. I'm good at dealing with being on tilt, but **** at the opposite.

My sessions tend to be of four types:

1) Terribly Tilting - I take a deep breath and if I think I'm getting agitated or off my game I just walk away from the session. The next day I'm all good - I'm fine with this, I don't think I can ever play well if I had a VERY **** session.

2) Bad but not horrible - This is probably when I'm at my best, focused on every spot, thinking clearly, making good decisions, unaffected by the fact that I might be negative on the session.

3) Okay-ish to good sessions - Also play fine, not as good as 2) but still fine.

4) Great sessions - I LOSE CONTROL. I've honestly started to walk away and bank because I know that if I go above a certain number of buy-ins + in the session I'm going to start getting very loose and making a lot of casual, "fun" decisions. The next day I'm fine.

Any tips to deal with 4)? I'm generally bad at "dissociating" from the total winnings of the session, but that's not really an issue except in this one case.
How do I start resisting the temptation to check my session's progress and just get into the habbit of "not thinking about it"?

I don't think there's a magic trick here. All you can do is be mentally aware of it and if you notice yourself slipping into that mindset try to refocus or end your session (like in case 1).

-separate your life roll from your pokerroll
-focus on playing good solid poker should lead to results anyway so why focus on the roll, the roll should be fine if you are focusing on the pokers
- this reminds me of a interview I saw with some pokerpro a while back he went for supernova elite every year (ah the good old days). He said he didn’t even looked at his roll for weeks-months on end, just was focused on getting the volume in every day and playing good pokers

Seems like you already found the cure. Get up. Walk away (don't forget your chips).
Find out if you need a day or whether a 2 hour break is enough to mentally consider it 'another session'.

...or just play tournaments