Help with code: KOER 1-2

[Evil Joe]

Apparently my computer is having trouble controlling the idle as I am getting a "1-2" code when in KOER. This is confusing because, to me, the idle and throttle response seem fine. I've read in the Articles Section that this can be due to coking. What is the proper way to clean the throttle body? I've tried spraying a ridiculous amount of throttle body cleaner AND carb cleaner into the T/B, but that didn't seem to help.

For reference:
1989 Mustang 5.0 AOD
145,000 miles
TPS: 0.9 V
Idle: approx. 700 rpm


Thanks,

Evil Joe