Well it sounds like a TQ converter problem. Honestly, there isn't much to these auto's, and unless someone just doesnt know what they are doing, not to much they can screw up. I've gone through a number of these trans, and unless they used used parts/didn't adjust bands properly, or maybe your trans cooler had bunch of metal in, didn't do proper flush before new trans install? Again, it sounds like TQ converter, but would like to know more details: Did cooler/lines get flushed? Do they keep reusing the same TQ converter, without having it checked/opened up? What ARE they doing to trans once it's pulled out/opened up/inspected? Anything? Or just looking at it, and putting back together?