MBMB

Sometimes when I come to a stop after exiting a freeway, my idle swings between ~500 and ~1000 two or three times before settling down to 775RPM (it's a GT).

02 sensor, MAF, and LH have all been replaced within the last 30,000 miles / 10 years.

Suggestions, please?

Speedtoys

Idle valve sticky.

FredR

+1 on what Jeff says.

When the ISV is "sticky" and does not respond to control action input, the controller adds another dollop or two of input and then when it breaks the stiction you get more opening than needed and the revs surge as the system does not respond as tuned for. After a couple of cycles the system starts to behave more like the manner designed until the next event.

I experienced something like this 16 years ago and was told I needed a new ISV. Took the inlet manifold off and inspection of the ISV port revealed a dry blackish powder in there with the shuttle sticking. Cleaned it out best I could with cotton cloth on a rod and eventually the shuttle started to move cleanly. Squirted a bit of WD40 onto the moving parts [no idea if this was a good idea or not] and put it back together- worked perfectly and still working to this day.

If you are still on the original ISV maybe time to consider a replacement and keep the current one as a fall back spare.

Rgds

Fred

MBMB

Would it make sense, when spraying cleaner down the ISV tube, to restrict the flow of air through the MAF so that the ISV opens and sucks in the Kroily goodness?