Ok, so I wanted to wait a little while before posting results, but I finally broke down (not literally) and replaced my IMRC. I just bought a new one from Tousley and installed it myself. Pretty easy job, only removed the airbox to disconnect the cable, then went in from underneath to swap it out. I reset the CEL and so far, after about 600 miles, the light has not returned. I think my MPGs are better, but it's kinda hard to tell since I ran in an autocross last weekend... I'll keep you posted.
So if anyone wants a slightly bad IMRC to try to take apart and fix, I've got one I'll sell pretty cheap. That way you can try the fix without disabling your car in the process.
SVT SQUAD #12 '13 Silver Focus ST3, moonroof
Old: ‘03 Silver SVT ZX5 #1459/2173, HIDs, Moonroof, Audiophile. Mods: Hawk pads, Waynes Tune, K&N filter
Older: ‘02 Silver ZX5 Premium, Leather, Moonroof