4.3gi high idle in neutral- ongoing saga- vid

[GHBAY]

Need your help please.

The solution is escaping me- certified volvo mechanic cant seem to cure it either...

After much effort tryi g to identify and cure the problem, i still have an idle issue.

Under load, in gear, she idles fine. After runni g, as i approach the dock and go into neutral, the rpms shoot way up.

Iac has been replaced. Thermostat replaced, hooked up to a comp and no codes.

shop keeps thinking they have solved it, then i take the boat and get the same thing.

The following vid shows me manually adjusting the throttle and you can hear it take a while to come back down. It doesnt come down like that when i do it from the helm, but is it as simple as this linkage? If you look closely, it does look a bit bent.

I have read vacuum leak can cause this too, how can i troubleshoot that myself? There is a bit of a vacuum-esque sound- not sure if you can hear that in the vid.

Open to any and all advice.

 

[GHBAY]

Tech says they measured the throttle and it was immediately at 0 when in neutral. Also says throttle body was pulled and all seals connections redone.

He is no wondering if it could be somethink with the intake manifold- although everything is torqued to spec according to them

 

[GHBAY]

It is a 2000 4.3gi with 308hrs. The motor was pulled last summer as part of the structural work and this was a new issue after that point.

 

[Tail_Gunner]

On the lower front of your throttle body there is vacum port take a reading from there, i have the same engine you should see 17hg of vacum second would be to take a voltmeter and see if your throttle position sensor is still working right
http://easyautodiagnostics.com/gm/4.3L-5.0L-5.7L/tp-sensor-tests-1

 

[dypcdiver]

Pull the split pin out of the throttle arm and disconnect the cable, restart it and give the throttle a couple of flicks to see if it settles down. Yes the end of the throttle cable does look bent to me. The fitting on the end of the cable should just slip over the pin of the throttle arm without resistance and the flat back of the end should lay perfectly parallel with the throttle arm and without any twist. Some on here say that they like to have a little closing resistance on the cable, but I prefer to let the throttle stop do the work it was designed to do.

If that does not help then I suspect you do have a vacuum leak. A length of 1/4" dia hose with one end at your ear and the other end probing for the leak makes a cheap and easy to use tool.