Alright, so I had a very noizy */C and it wouldn't make boost unless it was really cold outside. The minute it started warming up, it felt like the belt was slipping and the car would buck like a horse as soon as I went above 0 boost.

I replaced the coupler yesterday, the play is gone and so is the noise...but I still don't have any boost under load. The belt is recent (less than a year old) and it'* properly tensioned. I don't know what to do to troubleshoot this problem.

Is there black dust in the vicinity of the belt? That would mean excessive belt slip.

If you disconnect the BCS vacuum line that runs to the bottom of the BCA, does the boost return? If it'* bad, it could dump all your boost.

Can you get the fuel pressure tested? When my fuel pump was dying, warm temps and increased boost would make it buck, the the PCM would dump boost.