Brown sticky goo in airbox???

[ride92]

so I've been getting a bit of hesitation when I give the bike some gas while moving. Seems like it kinda bogs down. Last night I took off the tank to inspect the air filter and box and the attachments to the carbs. I found some Brown sticky goo inside the air box had kinda pooled in one corner and around one of the rubber boots. What would that be and is it normal? I'm thinking it's old gas that gelled up on me. anyhow I cleaned it out real good and put it back together. I believe the boots are seated well but they are a bit deformed and the clamps are old so they don't get super tight on there. I also saw that the whole time I've been running the petcock on "RES" so that may be an issue as well. I put it all back together and when I started I noticed that gas was leaking from the main fuel line that goes from the petcock to the little square thing behind it. The hose was old and cracking so I'm replacing that today. What is that little thing, it's like a distributor for the gas? One more question, I found some sea-foam, how much should I put in? Oh and the carbs looked really clean and the slides moved with out hold-up.