car cutting out

So, just replaced the iintermediate shaft bushing and seal, nothing else done to car, nothing disconnected. First drive afterwards, once warmed up car cuts out during transition from vacuum iinto boost. In vacuum, runs great, in boost pulls hard nonissues, its just right at that point where its at zero vacuum right before going into boost, and unless iI play with throttle it won't get past it. A/f ratios are good in vaccum and under boost. But when its cutting out a/f ra ios are lean..