'97 tranny problem

The Lumina 3.1 was running fine. All at once, when starting out, it wouldn't go above 30 mph. It would "cut out" in a sense, go back to about 15 mph, then go up again to 30 mph. It wasn't an electrical issue. I could tell it was tranny related.

Thinking it was perhaps a dislocated filter, or bad fluid, I drained the tranny. I found what appeared to be a broken plastic piece - in the shape of an arc, and about 6 inches long. The broken piece appears to be about 1/3 the size of what it must have come from (given the shape and size of the broken piece). The new filter and fluid didn't help, and I as assuming the broken piece is at the heart of the problem. Anyone know what this piece does? I'm also assuming that the tranny will have to be pulled to repair, but I know little about tranny rebuilds. It would help to know what this is and if it can be fixed without pulling. Is it related to the bands at all? Thanks for any input.

could you post a picture of this piece? that would help more easily identify what it is.

So it gains speed to a point, then slips outta gear and coasts down? Motor race when it drops out?

Sounds like you blew the accumulator seal or it could be part of the sprag or something...might be what you found in there...if you show it to a tranny builder they will know right away what it is, and what's gotta be done...