Today my 2007 KLX 250S with 7500 miles died abruptly (no misfiring, coughing, etc) about 5 miles after refueling. I limped home at 15 mph in 4th, installed new NGK plug, checked the air filter (100 miles old) but NFG. When I open the throttle, it goes to about 2500 rpm, then dies. If I release the throttle, it idles normally. If it stalls, it starts right up. The KLX is new to me about 300 miles ago. Is this a known "feature" of these bikes? Any suggestions for troubleshooting or fixes will be much appreciated.

Jim in Naples, FL.