Originally Posted by PorscheStrong

I had my 997.1 TT in for a wave of service items, including new spark plugs, new coils, new water pump, new thermostat, radiator flush, new fuel filter. In driving home, it ran fine at normal RPM's, but when applying more significant throttle, enough to engage the turbo's, performance severely faltered. Despite applying throttle, it was very sluggish to push up in RPM's, far too slow to accelerate, and created an odd sound out of the back - hard to describe precisely, maybe almost like a rapid thudding/slapping sound, very audible, but not what I would call loud. Putting aside the sound, the sensation reminded me of a clutch slipping in terms of lack of throttle response, though to be clear, there was nothing wrong with the clutch, just a similar sensation. No other hints from the drivers seat - gauges (e.g. temperature) were all normal, and no smells or fluid leaking that I could see.

Recognizing many of you are much more mechanically inclined than I am and you have much greater experience with these cars, I would appreciate your thoughts on what might be causing the issue. Also, anything I should be concerned about re: collateral damage? I'll have it back in the shop next week, but it would be really helpful to get an independent view from RL, just to make sure the techs are coming at this correctly (and if not, explore other options). My local indy is usually really good - specializes in P-Cars - so this is unsettling.

Many thanks in advance.