Welcome aboard. First - when you pulled the plug - was the electrode damaged/bent at all? If so, it's an indication of a bigger issue. If not, then the next thing I would check is the coil pack, see if you can find someone near you that would be willing to swap out one of theirs to test. It is worth removing that coil pack to make sure that the connector on the bottom isn't corroded at all, either...it does happen.

As for the boost gauge no longer working - chances are that you either damaged or loosened one of the vacuum connections. The first (and by far and away the most common) place to check is the "T" connector that is under the SC snout. It's notorious for breaking. If not there, then trace the hoses from each end and inspect along the way.

HTH

-Swash