There is a throttle stop on the coilpack throttle body that can be used as an idle adjustment. The trouble is that it alters the tps and will most likely never drop into closed loop idle if you go past around 10% which they're usually set at. If you have a standalone ecu like myself I can set it to wherever I chose and reset my tps in the software.
True, you can adjust the throttle cable to alter the idle but I would strongly advise the op against it as it can cause over/under revving and stalling due to the throttle never closing as you mentioned.
For the benefit of vinvindan, this is the Idle actuator control valve which will need to be cleaned. You will need a torx 27 bit to take it off.