A few weeks ago my truck, usually when started cold, starts at normal speed but as it idles it begins to speed up and a loud hissing noise starts. I can punch the gas a nd it will go back to normal idle speed and the hissing stops. I have also noticed a lack of power and with any load a very late down shifting (it will down shift if I let off the gas for a second).
I have attached two videos. One with it running normal, one with the hissing.

Any Ideas where to start?
Thanks

 

Did my videos not upload??

 

Maybe they attached this time.