85 weekender, fresh 2.1 swap, running issues

[wasserwerks]

Hi all, trying to see if I can find anyone who can assist in Connecticut.
I have an 85' weekender, freshly rebuilt engine from Gary from Suburban engine (done the Boston Bob way). By fresh, I mean it has about 300 miles on it now.
The engine mechanically is nice, I am having a weird issue electrically I guess and have gone through the bentley several times, as well as gone through many many threads of info on thesamba before getting information overload and having to take a break.
Here's what it does so far, starts fine, idles fine, accelerates great! Go two blocks or so, wait at a light, give it some gas, falls on its face. Have to wildly play with the throttle to get it to go, get around the corner, turn the ignition off and on, runs fine! This scenario can happen several times in a trip, or not at all.
So. I'm almost at my wits end and I know what the first few questions will be so I will list what I have done already.
Rebuilt 2.1L wasserboxer engine
Ignition switch has already been replaced
Overall timing set to 35 degrees advance (thanks Tencent)
Fuel pump: new
Fuel filter: new
Fuel: fresh
Fuel lines: replaced
Ground wire at left rear head: replaced w/2ga new (fixed hot start issue)
Ground wire at trans/mount: cheaned, checked, ok, but replaced anyway
Ground wire at battery: cleaned, checked ok
Ground wires at head: consolidated, soldered to new eyelets
Ground wires to chassis, under coil: consolidated, soldered to new eyelet
Positive wire at battery and starter: checked, ok
Hall generator: new
Cap/rotor/wires/plugs: new
Coil: new
Temp II sensor: new
Oxygen sensor: new
Idle stabilizer: new
Idle and full throttle switch (1pc. unit): new and checks ok
Auxiliary air regulator: checks ok
Air intake sleeves and main tb rubber all new

I know I need to perform a full electrical test as per the bentley, I have been extremely busy and have not had sufficient amount of time to do so. I would like to do one complete test when it is cold and then again after it has warmed up.
I checked resistance at the injectors, roughly 18.6 across the board, but that was before new ground wire and replaced eyelets.
Ok, after spending the winter in storage  the same issues apply. I checked a few things today. Checked the o2 sensor wire continuity to the shielding wire surrounding it. Ended up getting a reading but not when the wiring harness connected to the ecu. Checking voltage within 02 sensor while running, between .4-.6 when cold, down to .2's - .6 when warm. After about a minute of running perfect, the engine decides to do the same thing, burbling more at idle, way crappy throttle response. I unplug the temp II sensor, the idle smooths out but is creeping up in rpms. At this time it revs just fine, no hesitation at all. Plug the temp II back in, idle drops and gets rougher. Unplug the O2 at this time it does run rich. Plug it back in, seems to lean back out.
I need some assistance from someone.
Help!
Oh, the temp I and temp II readings at operating temp fell within bentley specs
Thanks in advance!

Oh, here is the thread on thesamba../vw/forum/viewtopic.php?p=5992261#5992261

[wasserwerks]

Oops, looks like i have to post twice before being able to add a link.

[wasserwerks]

http://www.thesamba.com/vw/forum/viewtopic.php?t=481253

[MrLiMBO]

Chris,,  I know you said you checked the voltage on the O2 sensor wire, but did you check the wire itself to make sure its not shorting out?? I've seen that issue more than once..  

Whats happening when you unplug something, as you prolly know, the ECU goes into an closed loop, or warm up mode and what ever sensor or wire issue you have is taken out of the circuit and the van runs better..  Unfortunately, the thing you unplug to make it run better is usually NOT causing the problem.  

I used to have a similar problem with my Vanagon..  You'll have to pin test the engine wiring harness and see if matches up with what VW says it should.. My gut feeling tells me its a wiring issue..

[wasserwerks]

Hey Jim, is that you?
Yeah this thing has been beating me up mentally. I get good readings on the temp II sensor at the ecu plug, so I assume its fine. I know its probably one item that's messing up the works. The only two things (or three) things I haven't replaced yet is the aar, the hall unit on the side wall near the isv box and the throttle body. The tb tests ok too btw. The o2 wire doesn't appear to be shorting out, but there is some resistance (Kohms) between the main wire and the coax, no resistance when unplugged from the ecu.
I have been swamped with work this week so I'll try to play with it a bit before dustoff.
Oh, it was a cali bus, so wiring is pretty clean, only old. I'd rate the wiring maybe an 8 out of 10. Its not pristine, but real good.
Thanks!