Idle drop when in neutral slowing down

Hi,

First, we don't offer this vehicle in the US, but I will do my best to help.

It seems a lot has already been replaced. When a vehicle has an idle issue, there are a few things I think of. First, the IAC which you replaced or the throttle body needing cleaned which you have done.

So, after that, I normally would take a live data scan tool to analyze the short-term fuel trims. If they are lean, I would be checking for an engine vacuum leak. If they are rich, I would first check the fuel pressure to make sure the regulator hasn't failed. Then a leak down test on the injectors to see if one or more is leaking causing the rich mixture.

If you haven't already, check for vacuum leaks. Here is a link that explains how to do it:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

If none are found and you have a scan tool with live data, let me know what the short-term fuel trims are at operating temperature and hopefully (LOL) idle or as close as you can get.

If that isn't possible, check the fuel pressure to see if it is too high or indicated a leak when you turn the engine off. Here is a link that explains how that is done:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Let me know if this helps. Also, let me know if there are any odd odors from the exhaust, smoke, or anything you can think of that may help me identify a possible cause.

Take care.

Joe