Yes..the cable lubers are worth it. You will never force the lube completely through the cable without one. It will also push out all the other junk and moisture with it. Its a bit messy but well worth it. I leave mine on, take it loose from the throttle body, drop a rag under the peddle, open the rubber up with something ..and let her graze. Work it and keep going until clean lube comes out.
The cable is close to the tunnel plastics so if you place a hair dryer or heater so it flows in there, it will thaw it...as that's the lowest point of the cable and where water connects. Look low on the firewall on the passenger side wheel well where the lines come out...that hole. Good luck. If you do this in the fall before it gets cold you won't have this issue any more.