<<need to get a very thin feeler gauge >>
Not really, just use your ears. Set it so that you hear it actuate
(click!) just as the throttle plate comes off its stop then make sure
you hear it reset (another click!) as the throttle closes.>>

Georgie,

Again you spew good information.

If you find that the TPS is clicking immediately as it is opened and
closed the switch still may require further adjustment.

And here's how to tell.

First make sure the gap is on the money
at the throttle stop screw.

Disconnect the TPS connector, and stick an ohmmeter to the two male
connectors.

Start the engine and at idle the reading on the meter should read 0.
Then slowly open the throttle, and the meter should go to infinity.

( this simple TPS check requires using a digital ohm meter )

Shut the engine off.

Now stick a goon into the Van, and have him / her slam the throttle
pedal to the floor.
It the digital ohm meter must read infinity again.

If it don't adjust the TPS till it does.
If it won't adjust, the little plastic cam is worn to the point of no
return, or the switch is DOA.

Replace both the cam and switch, adjust as needed, and the what you all
thought was the Vanagon Syndrome, will be no more.

What everyone seems to think is some sort of syndrome really isn't much
other than a periodic maintenance issue, and this switch does change
settings due to the plastic cam wearing out, and altering the TPS
setting.

It should be checked / changed once every couple hundred thousand miles
whether it needs it or not.

Ba-Ba- Louie