This is a very common problem on left hand drive Sportages. This is the first time I've heard of it occuring on right hand drive.
It's related to the engine wiring harness and the connectors Kia chose to use on certain engine sensors. They develop contact resistance over time which can result in wacko idle problems and usually no CEL.
First, is your Sportage OBD-II or OBD-I? I don't know what year Aussie models switched from OBD-I to OBD-II.
Here's essentially the problem: The connectors to the TPS (throttle position sensor), the IAC (Idle Air Control), and MAF (Mass airflow) need to be at the very least cleaned and re-crimped. The BEST solution is to cut off the connectors and solder the wires directly to each sensor.
The TPS is located right on the throttle body. Connector facing forward. The IAC is on the intake pipe that runs across the top of the engine. Directly over the exhaust cam side of the engine. Connector facing straight up. The MAS is the round unit between the air filter and the intake pipe. Connector on the back.
The hole in the exhaust is unrelated.
