This information is from mitsubi****echinfo website.
This code is tripped when there is a difference greater than 100rpm's between the engine speed and the "target" engine speed.
"TROUBLESHOOTING HINTS (The most likely causes for this code to be set are
*Throttle valve area is dirty.
* PCM failed."
It says clean the throttle valve area completely, erase the code and see if it resets. It says the next step is to replace the PCM. Personally i'd try replacing the throttle position sensor and motor before I did that.
This is assuming you've already replaced the air filter and checked the housing.