Before this happens, the truck bucks once as if it is going into low gear or something. Idles rough. This happened 4 times today while driving. Happens anywhere at any time, and just started about 2 weeks ago. I thought it could be ERG valve, or dirty filter, but I dont think so. My brother-in-law put it on a scanner,and no codes came up. When it happens, a small yellow light in shape of a socket wrench shows up.