I had the same problem , especially with AC on. I know you dont want to hear about the throttle body fix , but whilst I was doing this I noticed that all the piping for turbo , intercooler etc was loose & not properly sealed. I removed & cleaned all piping & then properly secured it back on the engine components. Plus checked all the rubber flanges for leaks. Result - No rough iddling. No stalling End Result - With this problem out of the way , and along with the many others I had , I finally decided to sell the ute. I know you've said you like the car but why should you put up with this type of build quality ? Good Luck