Hey. Possibly it could be the entire intake manifold. My car had a bad idle and was eating coolant so I just decided to buy the whole manifold(mechanic at my shops discretion). It was a good thin. I did because there is a small metal sleeve that runs coolant through there, and it melted a hole right through my stock manifold right after the throttle body. So I would at least take the manifold back off and see if it's melted or damaged near the sleeve. Could be part of the problem