I have had this code before. I cleaned my egr valve and it went away. My battery was disconncted when I cleaned it so i probably just dumped the code and it didn't come back till now. This is the only code that i am getting other than 10 and 11 during KOEO. My engine has been running like garbage, continuously stuttering at the 2000-3000 rpm range (if I power through it) and sometimes at idle. i have trouble shot the ignition system and found no deffects. I also have replaced my distributor, coil, plugs, wires, alternator to a 3g, and timing chain. to try and fix this problem but had no luck. So my question is can code 31 cause my problem and will a new egr valve fix it