High EGT Warning

With just over 200 hours on the engine, I've have started getting a high EGT caution indication on cylinder #1.  The other cylinders EGTs are similar, maybe 10-15 deg cooler.  The caution is set at 1600 deg F.  The engine runs smooth and lane checks are good.  This is a new issue for the aircraft, and has not happened in the past.  

This occurres in the upper power band of ECO mode, and pushing into POWER mode drops the EGTs into the 1450 deg range.  Backing off the throttle to a lower power setting, say 5150 RPM in ECO mode, drops the EGTs about 20 degrees to 1580 deg.  All Spark plugs were changed at the annual inpection a few days ago and it made no difference.  The plugs that were removed all look good and similar in color. 

The only thing I have changed is fuel.  I recently started using a 92 octane alcohol free fuel (pure-gas) from a smaller supplier, whereas previously I used Chevron 91 with 5-10% alcohol.