i know that i don't know alot but i had the same prob at a stoplight with the hunting. i know that it sounds stupid but start the truck cold take the rad cap off let it run and cycle for about 45-60 minsleave the heat wide open i did this and this fixed it. the little bit of air was causing this. i have had many people ask me this. i have told them the same thing and they did this and it stopped. just hear me oout and try i know it sounds like alot of time but you need to do this because of small amounts of air in the block.
good luck
it will bubble a little but keepthe rad full to the top the entire time.
