I just did mine this weekend with my LS/vtec. I replaced the IAC valve and then found out that the fast idle valve had unscrewed itself(unscrew the two 8mm bolts,slide the plate off and the vavle just fell out).. i had the same surging idle 1k to 2.5k rpms and then fan kicks on and then idle'd at 1800rpms. but now that fixed..but i thought you was to screw that valve till bottoms out and back it out a 1/4 of a turn and close it up and then adjust your idle air screw. hmm well anyways its running fine now.