[Miataracer]

did you take the valves out? if you were cleaning the ports with the dremel and wire brush you could have possibly just got some loose carbon proping the valve open a little bit... if that is the case it will make its way out of there on its own.

I know this would be a real bitch but you could also carefully take the valves out and make sure you know where they came from and lap each and every one of them... this would give them a like new seal on their seats, but since there is 16 it would take a while. also, you have to be careful to get ALL, and I do mean every bit of the lapping compound out of the port areas... that stuff is not so good inside the engine

side note, the valve seals are only there to keep oil from getting past the valves and being burnt in the combustion process... the valve "seal" you are speaking of is the seal between the valve itself and the seat the valve rests on when it is closed, this seal can be renewed as previously stated by lapping the valves