1997 Mercury Sable sable wagon speed sensor VSS

Hey guy,
I have a sable wagon. Here are the symptoms
Trouble shifting from 1st to 2nd
Speedometer jumps around. Doesnt work until im going 35
Hard, clunking downshifting
Pep boys diagnosis was output speed sensor. Midas replaced it. Engine light went out but problems are still there. Any ideas? Engine light back on. Also hear a rattling but that could be anything

Thanks to all! I appreciate your advice

KDJ