Hi! i will start by saying sorry for my english (i am swedish)

I have alot of problem with my 2007 Suburban 1500, 5,3L, 4wd. But my biggest problem is that when i drive at any speed the car can go down to idle rpm, even if im rolling down the highway at 70mph. When it happens it sometime jumps back up to de correct rpm by itself, and sometime i have to let go of the gas and tap the pedal (if i press and hold it down i will takeoff like a rocket when it jumps back up xD ) i had this problem before but now for a couple of month it have been just normal until yesterday it started again plz help!

plz question me if you want more info

// thanks beforehand