Hi,

Yes, I think you need to sit down with the priest, since you have your Bentley bible.
If anyone can decipher a book, that hundreds of years old and get any worth out of it, a Bentley should be a snap!
Both the Bentley and the Bible both have their errors even though they are supposedly “good books” will still have their flaws!
Both came into being as what they are, while being written and interpreted by several men learning how to write up something that changes with evolution!
Absolutely very Tricky to get right without proofreading and collaboration during the dark ages!

Had to be tough stuff to do with out bottles of “White-Out” or the spell checking by candlelight on scrolls ... let alone the use of quills and ink!
I can remember those Sheaffer fountain pens being a mess!
Especially, if You slung the tip at someone! (:)
Penmanship turned into marksmanship!
No ball point pens were around until about junior high school for me!

Also Remember this. it’s been proven that “molds” grew in the cheaper (rye?) bread flour that the nobles didn’t eat but the monks did! All of that was in a neighborhood near Transylvania!
Just how far is Transylvania from those Swedish Vikings, with pointed noses, that Walt Disney likes so much?
http://nordicmuseum.org/events/nordic-stories-dec18

Ok serious stuff now!
Since the engine seems to be better with the new knock sensor the ECU must be working with a RPM signal. This is very important for the ECU it to talk to the IAC.
You need a good throttle switch to be adjusted to be “right on Position to the throttle plate.

You want the plate shut but not jamming in the bore only tightly shut.
There is stop screw but is only there to keep the spring pressure on the pulley from jamming it down too tight.
There is a specification, in the Bentley, but like the Bible, it’s wrong or is a vague in statement for most readers.
After touching up to the stop lever, turn it only about the width of the screw slot that’s in the head to 1/8 of a turn and lock it down with the jam nut!
Do not let hold it open at all because all of your idle air has to go through the IAC so it bypasses the throttle plate!

Since you are cleaning the throttle body, now is the time to get those two things set right.
Using an Ohmmeter on the switch while watching for a changing state across two terminals tests the switch and your hearing.
I don’t remember which way it goes, closed to open or open to closed.

Get this done as the plate cracks open from being totally shut! I mean you just barely noticed it wiggle open as the switch clicks or the readings change when you “think” you saw it open!

The ECU cannot see when you open the throttle. Yet, it needs a heads up that it’s happening like right now! The airflow changes there super fast and is very turbulent of which works the FPR for more fuel.
Otherwise, it has to wait for the AMM to send a signal.
In most cases, that is not enough information for the ECU to know you are wanting power and not the idle mode program any longer. This Is one of a few reasons for hesitation or stumbles.
A bad accordion tube behind the AMM is another.
Use a bright light down the center and wiggle it for cracks, splits or pin holes. The ends must fit smoothly and tightly under the clamps.

The IAC. Is the next culprit to rule out.
Notice when starting that it must raise the idle up, all by itself, well above the normal 750 idle speed and then move it immediately down to 750 and hold it there.
If not, it’s bad or not working from being stuck or sticking from wear or smut from vapors.
You will want to refrain from using that black knob to bypass any air except when setting basic idle speed when using the blue wiring to lock out the IAC.
The knob is there to just keep it limping under the lowest speed the IAC has while restricted.
The IAC, when released, has to be just above the completely closed throttle plate speed.
When the transmission or A/C is engaged, it must be able to add more air or have the range to open for the loading and still hold the 750 rpm!

On the 1986 it uses a “three” pin connection. It uses 12 volts to oscillate by reversing polarity between two pins. The unit does not have an internal reversing spring like the later cars using only two pins.
I use a nine volt battery to simulate a cranking systems voltage. Using straight 12 volts slams the vane as hard since when it might be sticking.
Using 12 volts is ok during cleaning but not for my final test for lots of wear.
Worn out is when the brushes on the inside stick in the far ends of a tapered groove created in the armature from back and forth wear.
The most wear of the armature is in the middle of the rotation and less at the ends.
The brush is still wider as it continues to wear downward.
The Sticking at the ends slowly occurs and is unpredictable. Sticking and arcing gets worse despite cleaning the vane or wishful hoping it was the cure!

It is time to replace it because as far as I know, the brushes and armatures are not readily available or rebuilds would be on the market.

Good luck on getting the last of those green, pointed nosed, gremlins out of the way.

Phil