funny noise at idle

[getcrunk88]

i have a 1995 gmc sierra z71 with a 350 and almost every time i start the truck it stumbles very little but it sounds kinda like a misfire i can only hear this happening at idle and when the misfire happens it sounds like an air leak somewhere what could this be other then that the truck runs fine plenty of power just sounds like a valve is stuck open forcing the gas air mixture out the intake mani mabey. If anyone has any info i would greatly appreciate it.