On the firewall harness connection, you need to pull the bolt out and separate the harness from the firewall. If the power feed wire has been hot, you be able to see it. The goo is a sealant made from some sort of tar based material. It's been a while and I don't really remember all the details of your problems, but a carb rebuild is next on your list. Get it really clean, find a soak tank if all possible, if not use plenty of carb cleaner in all the passages. Once you get it rebuilt, replace the spark plugs and 90% of your problems will go away.
