Ummm... Yeeaahhhh...
After I posted in the thread that Steve just linked to,
I later found out that gas Precedents don't have an electrical components box!
I still don't know Precedents very well, but I had heard that you can disconnect one of the wires at the GCOR to make it idle.
(GCOR= a micro switch block located under the floor panel at the GO pedal.)
But, after looking at a Precedent wiring diagram, I'm not all that sure that'll work either!
I have yet had the chance to play with a Precedent to figure out how to do it!