I'd trace the wiring back to the ECU first and then check out the throttle valve. Why did they say the throttle valve was bad? Is the CEL on and a code stored for it?
BTW, if the throttle valve is bad, a new one is about $250 from firstvwparts.com (a VW dealer with internet sales). Your local dealer may charge near to twice that for this part. I know. I had to replace mine.
Unplugged, by default, it stays open, but you will get a CEL. The car runs fine without it. Its sole purpose is to increase EGR flow rate into the engine and quite the engine on shut-down. I think it may also offer some protection in case the turbocharger fails and dumps lubrication oil into the intake manifold, which could cause an uncontrolled engien acceleration.
The best option is to have it working, but there are other options, especially if you do not have to pass emissions testing.
--Nate