i recently had something jammed against the window on the driver side, it kept catching the window on the way down and up, so i took the door panel off, and found a piece of steel, bout 12 inches long with the same material as the window weather stripping, i cant figure out where it came from and since its been off, i havent noticed a difference is functionality, is it a nessacity or no?

 

Yes, its the window glass rear run channel. It should have a bracket that bolts to the inner door panel just above the vent. Without it in place and the window rolled all the way down the glass could move rearward and jam.

Ref Item #6