well this just started when the weather up here in minnesota stays in the 30. I get out to my truck after work tonight jump in and i let it run for a minute before i take off the rpm were fine until i get to the light it stay at 2,500 Rpm then it will drop back to the oem rpm specs,then when i got home put in park the rpm shoots up to 3000 rpm and now it stays there! i check the throttle to see if it was sticking but no,what could this be? also the transmission seems to be slipping on its second shift (auto 5r55E)

 

how fast does it go? plugged exhaust/cats?