Q7 Issues

[Borat]

I have a 2008 Q7 v6 3.0 sline tdi. It flagged the p0638 so removed the throttle body to check it. The unit was seized so i replaced it with a brand new one. The fault code was cleared and driven. A few starts later the same code was back. I returned the throttle body and got another one from different company. Same again works for a few trips and fault Code comes back. I have tried throttle postion reset on diagnostics softwarw but says ok but fault clears and keeps coming back. Please help me with ideas am i missing something???