Hmm. Like others have suggested, the CHT might be the cause. Since the CHT is a NTC resistor, its resistance drops with increasing temperature. One thing you might want to look for is to see if the spade connector from the sensor or some other exposed part of the wire is touching ground. Grounding the CHT produces a very lean mixture. Use shrink-wrap to insulate all exposed areas.
When hot, the CHT should measure 50 to 100 ohms. If you're measuring significantly less than 50 ohms when hot, then the sensor is likely bad. Check my D-Jet parts page for the correct replacement part.
Brad Anders
http://members.rennlist.com/pbanders/djetparts.htm