2007 crown vic goes out of gear when i stop

I got a 07 crown vic it starts and runn great only problem is i have to rev up to like 3k to get it to.go into gear once in gear everthing shifts fine it dosent go out of gear when you keep it in overdrive and stop buy in drive without od on it goes out of gear and i have to rev till it slipps in gear, got a p0720 code output speed sensor but idk if that will fix it anyone else jad this problem ever find a fix?