I am assuming all tensioner components you replaced were new?
Sounds like the bushing attached to the tensiouner shock has worn out. Typically announces itself with a clanking sound at idle but smooths out when driving.
About $2 fix if this is the case. One test to perform is to take a screwdriver and apply pressure to the shock mount while the engine is at idle and see if the noise goes away. If it does, there is your problem...
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car