If you're idling at 1,400 that's more than a vacuum leak. Vacuum leaks are unmeasured intake air and generally cause rough running problems, not raised idle. As long as the throttle position switch is adjusted properly and working, the ECU will use the idle air valve to maintain idle at around 900 no matter how rough it's running, more like 950 if the A/C is on, a bit higher initially dropping from around 1050 for a really cold engine. High idling problems are often due to a bad signal from a failing block temp sensor (rearmost of the two under the intake manifold). The other possibilities for a bad/unstable idle speed are someone tinkering with the throttle body stop screw, misajusted linkage rod or throttle cable, a misadjusted/disconected TPS or a faulty/disconnected IAC valve.

For unmetered air from vacuum leaks, there's split/disconnected PCV vacuum lines, the vacuum lines to the brake booster & bad check valve for the cabin air vents, with a lesser chance again of it being a diaphragm leak at a vent actuator. For the latter, disconnect and plug the port on the intake manifold to see if running improves. Other sources of unmetered air are a leak around the throttle shaft as you note, and a major source could be a split accordion air intake hose -often out of sight underneath.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Hi,

I have never changed one of those either.
I doubt the spring can be very complicated.
Just mark which notch that the tail end of the spring goes back into.
This will bring back the same tension back to a gas pedal feel as before.
Otherwise you may not feel the feedback to know how much you are pressing on it.

I doubt you have worn out a seal to cause a maximum of 14” vacuum.
The idlIng point vacuum should be a lot higher.
You are not looking in the right place. IMHO.
That shaft clearance is way too small.

An intake manifold gasket is more likely the culprit or if recently done the install was done incorrectly.
Like having a wire caught under it upon replacement.
A compression test is more warranted in this case for valve issues.

I have heard of the smoke test doing that before but never read any feedback as being a problem.
First of all it’s about volume in your case. A faint tail of smoke is not a forestry fire but a camp fire.

We need more background information to help you.


While you are there clean the throat of the throttle body out as it helps keep things transitioning smoothly.
Having it adjusted to the electronics is an important step.

Phil