I have an intermittent problem with the TQS which I am hoping someone may have a suggestion of where to go next with!
Basically, the revs will suddenly drop when idling and then hunt without cutting out,seems worse when there is a high ambient temperature or been sitting in traffic. Also when the car is having an 'episode' when you try to pull away it struggles and you have to rev it over 2.5k to pull away or it stutters, also it is well down on power and you can hear the turbo spooling but not reaching full boost.
It will then go back to normal again and drive like nothing is wrong!
I took it to a Audi specialist who plugged it in, only 2 faults logged, an intermittent over boost and an intermittent n80 problem. The chap chap ran a test on the solanoids and all worked fine. No obviously boost leaks or split pipes
Ive now replaced the n80, cts and cleaned out and reset the throttle body
Anything else I could try, I'm running out of ideas now and it's driving me slightly nuts!!