Sounds like you've fouled something, though cold temp swill affect your idle anyway. You might want to take a good look at your cooling system/thermostat/water temps/fans while all this is happening. If the engine isn't warming to proper temps, it will try to idle high. Check the heat range on your plugs too. Could be weak coils, exhaust leak, etc.
If the car never idled poorly before, you need to back-up and determine what made it change. Even in cold weather, the car will behave about the same at idle once its all warmed up. The injector cleaner is unlikely to have changed anything, for better or worse, in that short time.