99 cougar trans or valve issue?

My 99 cougar shifts a little hard. In park the idle fluctuates around 200. I have to check to be sure. While I'm driving it, get it up to speed, it goes to 3rd gear fine. It's doesn't go back down to second gear when it should. While its in 3rd, the rpms are at 2000. Is this normal? Right when I stop it it shifts pretty hard to first gear. It shifts the hardest coming to a complete stop. I take my foot off the gas and it basically drives itself. Maintaining the speed I was doing. How do I check to see if cruise control is off? Could it be in overdrive? Also It makes this humming noise kinda like a vacuum cleaner. I read some forums on ask.com, says its an engine valve. Just hope I don't need a new trans. Any suggestions??

Hey buddy if it's shifting hard I would try changing the speed sensor AKA neutral safety switch
http://www.fordparts.com/Commerce/CatalogResults.aspx?search=true

check out this part number on the diagram, this it what im talking about and it shows you were its at

Callout Name: 7F293 Part NumberPart DescriptionPrice


7F293
(SW5438)
http://www.fordparts.com/Images/Logos/FordMotorcraft.gif
Auto Trans Gear Position Sensor
CD4E ``BEFORE 05/09/00''
$47.29