when car first starts it idles around 1100 rpms which is fine but then after driving it..the idle feels like its stalling and jump like 500 rpms,-800 rpms jumpy then the exhaust sounds like a go kart...i think i may be running on three cylinders or something any of you had this problem? just started yesterday...could one of my plugs be fouled? would that cause this?

 

compression test it