Pulled it all apart, cleaned the crap out of it all with brake cleaner and scuffed the joining surfaces with #000 steelwool, light film of grease and blue locktite on the bolts.

Stem is aluminum and so are the bars. They were both new so they hadn't been mated up to any other stem/bar combo.

So far everything sounds good. We'll see in a few days I suppose.

Thanks all, NAES