I had the wonderful opportunity to replace my rear cam seal, oh what fun, NOT. Had to pull the intake and rear valve cover and cam cap to get the seal out, it was beyond jammed in there, tried drilling and pulling with scews and picks, no luck, so did the removal. Anyways, after putting the manifold back on, which Ive done several manifolds now, I have an occasional misfire at idle only. Rpms are normal range . I've checked everything 3 times and don't know what it is, just frustrated. There are no codes btw.