2.7l Cam Timing trouble

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We have a 2002 Allroad 2.7l twin turbo which had the common oil leak at variable cam timing unit gasket.  When we went to change gasket, the tensioner for CYl 1,2,3 whould not freely release and we found a small piece of aluminum inside so ordered and installed new tensioner.  We ran vehicle a minute then suddenly ran rough and missfire 4/5/6 codes plus code for cam/crank timing trouble.

Tore down again and found timing between the two cams was off a tooth (reportedly common as oil bleeds out of tensioner when engine shut off and pulley can jump s tooth).

We reset chain timing and once agian ran engine for a few minutes in shop-- PERFECT but one mile down the road, same MIL lamps and rough idle.

We tried another cam position sensor, no change.
We suspected a defective tensioner but no mechanical evidence and our supplier says that they have never seen a defective new one?!?!

Any tips or comments are appreciated.