It, i.e. the mixture screw, has basically NO effect above 1500 RPM.

87 911 3.2 idle
 

I can’t adjust the mixture at idle.

Does it not change? If i were you I would install the chip adjust the idle and mixture with the bypass jumper installed, it takes fiddling with both to get it right. Double check the idle switch. And check the o ring on the throttle body idle screw.

Easy way to check your vacuum system (I know you say you smoked it) is to pull the oil fill cap. You should be able to hear an audible drop in the idle. The jumper you're referencing is the one you do on the left side of the engine compartment? I think that bypasses the idle air control valve. If the car smooths out with that jumper in place, take the IACV off and clean it.

Your readings at the different throttle stages seem a bit off at WOT. I was thinking the car is supposed to drop into the 12's at WOT and 13's at tip in. Mine with a chip will drop into the 11's when I'm at WOT

87 911 idle
 

Bump

I had the same sort of issues with rich and surging idle on my 3.2. It turned out someone had adjusted the cog wheel spring in the air flow meter (AFM) to compensate for an older custom chip I presume. I could wind out the mixture adjustment screw 8 turns or more but it was still too rich at idle. With the spring tension tightened two teeth I was able to get a nice 0.8% CO mixture (14.2 AFR) with just over one turn out from full in on the AFM mixture screw.

Does it look like the AFM has been opened before? If so you may need to carefully adjust the cog tension to get mixtures right by monitoring each change with an AFR gauge as mixtures will change across the entire rev range. As some one else has said if you intend on doing a chip change I'd do that first before mucking about with the spring tension.

Check out this previous thread

http://forums.pelicanparts.com/porsche-911-technical-forum/1053438-carrera-3-2-idle-mixture.html