XT600 idle problem any advice?

got a 2000 model XT600 and it has an erratic idle. Normally sits at 1100rpm for 15-20 seconds but will then shortly fluctuate up to 1400-1500rpm and then as low as 950 rpm before returning to normal. Runs well otherwise. Starts instantly and power is good. Any suggestions before I start to test air, fuel, spark.

Carb boots

That would be my first thought as well!

Thanks. Luckily I have a new set available. Will put them on see what it does.