When you say you disassembled it did you remove the disks and floater? If you did and you flipped any one of them then you are not getting full contact anymore. Brand new they are perfectly flat but once you run them they become concave. This is likely the issue. Only other option would be contamination with oil. The overheating issue is from excessive slipping. The “stop accelerating” at 9000-9200 sounds like you are describing the stall speed. Assuming it is a can engine it should be closer to 5
8600. You should not do more than 2 clutch tests in a row without letting the clutch cool. Even if engagement is set correctly it will get very hot! The quick fix is to take a 1/4 turn counterclockwise from each spring to lower engagement. Assuming a plate is backward it will be hard to determine and correct now. Ifeal fix would be to get new disks and floater and have the clutch re machined flat with .030 air gap and start over.