Lately Ive notice bad gas mielage on my 87' turbo II, so i pulled my new spark plugs aftert 600mi and they were dark. Then when i was trying to pull my cat i reallize that my o2 sesor is not connected to the lead, the connection broke off. what is my car doing right now as far as mixture?

 

running rich, which is why you got crappy gas milage and performance.

 

Exactly. Repair the connection, get a new sensor and plugs, or else this cycle's going to repeat itself.