everything in the drivetrain is either new or as good as new. All cables and housing has been replaced with teflon lined SS stuff...no kinks, nice big loops so no kinking and the line into the cable stops is straight too.

So far I've tried a few different chains, cassettes and last housing loop to RD. Shifters are as new and I've cleaned them out so ther's no drag in them at all. RD has had a solvent bath and new lube applied.

I have put together my share of bikes and this is the first time I've had this happen. I'm out of ideas.