High idle, sticking throttle, throttle body questions

[SJ]

Patient is a 1990 100q     non turbo, manual transmission

Here are the problems I am experiencing.

1. Idle is at 1200 rpm

2. Unintended acceleration: After pressing the gas pedal past a certain
point (secondary throttle valve activation), the throttle wont return.
Noticeable on shifts - the RPM climb to 5k.
Letting out the clutch will reign in the RPM's, but sometimes the throttle
is stuck until you stomp on the gas pedal to release the throttle. Thats a
bit scary.

I traced the problem to the throttle body. There is friction in the moving
parts and the secondary throttle plate does not close completely. The
primary throttle plate closes ok.

Now the questions:

1. Idle switch - I read 8.0 ohms instead of 0.0 with contacts closed. The
reading is consistent. I read in the archives about cleaning out the
contacts by drilling a small hole in the switch body and spraying in contact
cleaner. How effective is this procedure?

2. What is the purpose of the dashpot? I know it slows down the closing of
the primary throttle plate by about 1.5 seconds. Why is it necessary?

3. The adjusting screw in the primary/secondary linkage has no head. It
looks like the head was sheared off after the factory assembly and
adjustment.
The secondary is activated by the primary shaft after it goes thru about 25%
rotation. A slot in the linkage activates the secondary.


SJ
85 Dodge PU, D-250, 318, auto
85 Audi 4k - - sold but still on the road
88 Audi 5kq
90 Audi 100q