Idle-Up Valve, Or is it Air Bypass valve????? Options

[Spider77]

OK. So ive been having this massive problem with my car when Im running the AC. While im driving its fine (save the the noticable loss of power). When I come to a stop, the whole care shakes like a nanny on a baby. So i did some reading about my "Idle-Up Valve" (or air bypass valve as toyodiy calls it). Why not take it out and do some resistance readings accross the terminals, they turn out to be fine, but I noticed this adjustment screw. I turned it all the way to the left (pass side), and turned the car on, ploped it in drive then turned on the air. Well, idle dropped to 200-250 ish, car almost wanted to die, but the air was still going. Went out and adjusted all the way to the other direction (driver side) and all of a sudden whe nI run my air, my idle dosent drop like it used to (used to do about 100 or so at stops. I used to press the gas a bit just to keep from vibrating so much).
My question would be does anyone have any info about the adjustment screw on this thing? It was marked at the halfway point, but I think all the way and back a bit it runs soooooo much better. I just dont want to jack anything up down the line by having it adjusted "too far".
Thanks