Hey Guys hope this helps alot of you out for this method is a little different than most described on this site but worked a treat for me. My father use to be a mitsi mechanic until he went holden and told me how this is done and that it should work on most late model Mitsi's.
1st - Disconnect battery for atleast 10 mins. (Resets ECU to factory)
2nd - Connect battery
3rd - Turn car into on positon (DO NOT START ENGINE)
4th - Wait for necesary lights to turn of on dash turn off stereo and aircon
5th - Press acelerator hard to floor for 30 seconds
6th - Take foot of accelorator for 30 seconds
7th - Start car ( dont use acelerator if you can help it I did not need it)
8th - Leave running for atleast 20 minutes

As I said worked a treat for me, Hope this helps
***If you still have problems clean out throttle body with rag a and cleaner this can make a huge difference***

Funny enough, a few days after you posted this, I took my car in for its 2-year service (including brake fluid drain; also asked them to check/clean the throttle body and EGR valve), and as the battery was on its last legs (good run - 6-7 years) I asked them to replace it.

Now, I didn't have your post printed as I didn't expect the battery to need to go.

Last time they disconnected the battery, the car was left idling for a while, but the idle still dropped as I drove back to work after picking it up. I expected that again, but this time, I saw the car with the ignition left "on" without starting it, and I think the car was idled for only a few minutes while I paid for the service and had my service book stamped.

Drove back, and never had a problem. And that's a European/BMW specialist mechanic I usually go to, so perhaps the number of Galants they service meant that they know about this.

I mentioned about your post to the owner of the place, and told him I'd send him a copy of your post. There must have been elements of your 8-step process which were really critical to making sure the idle doesn't dip while driving, given that I'm sure they didn't do everything you mentioned.

Thanks for the info!