my dad bought himself a Nexstar ARF plane. it came with an OS 46. the first time we flew it we had experienced pilots tune the engine. so iknow its tuned correctly. Ok so we rev it wide open on the ground, we see air bubbles in the tank to engine line, but its not affecting th engine so we fly it. In the air the engine was racing every once in a while like its overspeeding, its like the bubbles got into the engine and leaned it out. and then we had it die and we had to dead stick it. but wehave no ideawhats causing these bubbles. the fuel tank looks perfect, all the lines are perfect. and we have no modified it in any way, the tank is in a lot of foam. Anyone know what the possible problem is here?