vx ss Intermittent idle problem

[v8commodore]

Hey got a vx ss commodore auto cammed etc etc. Car was idling fine before for over 6 months had to take it to a different shop as there was a few problems with it being lean and rich. So it had a full retune car is running better then before but now I got it back when i start the car and turn it back off sometimes it will stall when you put it into Drive took it back they fixed that problem but now it wants to idle really low like its gonna stall only when car is cold once warmed it seems good. But sometimes it just wants to idle higher eg driving at 60km back off car seems to keep driving it self takes few secs to come back to normal idle which is 950-1000rpm atm. Tune has been checked had a new IAC put in it few months ago. So its back at shop again looks like IAC could be sticking??? Being pretty new didn't think this would happen but IAC counts I was told should be around 40-70 mine are on 5 last time was checked. Removed IAC plug car idle same no difference any ideas what to look at thanks.