1991 Chevy Corsica. 3.1 v6 issues
 

Ok first off I bought the car a few months ago. It only had 50,000 original miles on it. The problem first started when I plugged the tcc back in so I redisconnected it. Then the car when I filled up pored about 5 gallons or so of gas on the ground. Then when it got cold out in my it wouldn't start. And it gets poor gas mileage as my silverados would. So here it is
1) how can I make the gas mileage get better? (Has new spark plugs, wires, oil change. Always do that when I get a new vehicle)
2) why would my car not be starting when it gets cold even though the battery was bought 2/14?
3) the car has cruise control, but when I turn it on or try to set it nothing happens. No light no speed hold. I checked all vacuum lines etc?
4) there is a tube coming from the valve cover on the front of the engine to the air intake duct that hooks from the air filter box to the throttle, and when I take it off to do anything I find oil in the air duct and oil going into the throttle, what is going on there? I know it's probably not right