All, I have been attending to other matters for a month or so but am now back to addressing a few issues.
To refresh, I am working on two cars, one '86 and the other an '89 (with Lucas ignition). Both BRG with tan interiors.
The '89 finally got the sway bar reinstalled with new end link bushings. Needed the help of a friend to compress the gap with a crow bar to get the nuts on.
Fuel rail with re-furb'd EFI's, filter baskets, spray tested, and new "O" rings all installed.
Last item is to bleed rear brakes per ABS Teves specific procedure. Two man operation. That should do it for this car.

The '86 has three issues I am having trouble with.
Background. Car ran very well. Smooth, strong. Developed an issue with not shifting into 3rd gear. Very experienced, reliable local trans shop re-built the TH400. Shifts smooth now .......but the car idles at about 2600 rpm. Can't figure out how to bring the idle down. Today we tried adjusting the AAV screw. The car started surging like it was searching for a correct reading. It was oscilating between 1000 rpm and about 2500 rpm in a fairly rhythmic pattern.
No idea where to go next.

2nd issue: Wipers. No power at the multi-point plug. New fuses in all positions including #9 turn signals and #11 Wipers. Power registers on all fuses except #9 and #11.
Broken wire somewhere? All other electronics (except internal fan Hi speed and Oil Pressure gauge) are working. New wiper motor is ready for installation once power/wiring is solved.

Once these issues are resolved this will be a very nice car.

 

For this I would begin with the basics:

Make sure the throttle bodies are clean and the throttle blades set to the proper .002" gap.
Adjust and synchronize throttle linkages so both throttle blades are closed at the same time and both open at the same instant.
Along the way exercise the linkage and throttle turntable to make sure there isn't a mechanical problem holding the throttles open. Take a look at the nylon bushings at the throttle bell cranks at the rear of each intake manifold.
Check for a vacuum leak....a fairly large one in this case.... such as loose bolts holding the air cleaner housings to the throttle bodies.

If no joy then we'll dig deeper.

Cheers
DD

 

OK, your surging symptoms first:
The ECU stops the injectors when the throttle is closed and revs are above 1400. ie, throttle is closed = TPS reads 0.32v or lower. Once in the closed throttle condition/no injections condition AND the revs fall below 1400, the injectors are switched back on by the ECU. Once the injectors switch on, if there is still too much air, the revs surge above 1400, ECU switches off injectors, and so it cycles.

So I think that your TPS may repeat may be giving the wrong signal, AND that you have a massive air leak somewhere.
Your revving at 2500 must indicate a massive air leak at closed throttle, as (closed throttle revs above 1400) the injectors should shut off the fuel. The the fact that the revs started surging after you reduced the air 'leak' by screwing in the AAV adjuster indicates the ECU/injector cutoff is working, but somehow was being overwhelmed or over-ridden by the air leak and/or the TPS being out of adjustment, or faulty in some way.

That is where I would start, and why, as Doug indicated above checking the butterflies, then I would go round EVERY entrance into the intakes: cross pipe and hoses and vac takeoff to ECU, vac spigots, fixing bolt tightness to the heads, throttle body bolts, vac takeoffs under A and B bank (notably the Cruise Control large diameter pipe). Somewhere, for sure, is a big leak.

 

Adding my thoughts.

To get the trans out, humans have been reaching down the rear of the engine to get at bolts etc.
That can easily dislodge/mess with, the hoses on the balance pipe, and the notorious 90deg elbow on top of the AAV.

Then the wiring back there, oh boy, time needed there. NOT a common screw up, but Freddie Fiddler can reek havoc.

 

Okay, Great info. Gives me info on where to start. I am sure I will trace it down and get it fixed.
Then it will be on to the wipers. lol
Thanks All. I will keep you posted.

 

BTW .... I did replace the throttle shaft bushings and set the butterfly valves to .002 per spec's last summer so I can cross those off the list.