ok, thanks. I'll do that. Just to confirm a few things (and some new information):Spark gap tester to see if your missing spark. If spark is there than we look for fuel. Place on coil feed and if good there, move to a few plugs
1. By spark gap tester, do you mean an inline spark testing light, or one of those testers that actually has a gap for the spark to jump? I have both so happy to test both. If you mean the one with the actual gap, what should the gap be set at for this test?
2. Another question. I noticed that I have a main breaker on top of my engine. It's a 50A breaker and sticks out like this:

Is this normal? It doesn't seem like it's tripped... I can push it in like 1/16 of an inch and it bottoms out, I can't get it to push in any further. And when I look up this breaker online (west marine, etc.) they are all sticking out like that. It'd be weird for them to all has photos of it tripped, which makes me think that this is just what it looks like. But would a tripped breaker let the engine turn over strong but just stop the sparks from firing?
3. I sprayed some starter fluid into the spark arrestor... I assumed this would essentially function like the air filter on a car and would get starter fluid into the air intake. If this is correct, it did NOT fire with starter fluid, and I put a fair amount in there. I thought i heard it pop and definitely got some white smoke out of the spark arrestor and it smelled like burned starter fluid, but it didn't ever actually catch (and may not even have popped, that might have been my imagination)
Thanks. Really frustrated... it has been running with that misfire for weeks and then over the course of like 5 minutes of runtime started running worse and worse until now it just can't start. Really annoying to watch :/ looking forward to fixing this and appreciate all the help!