I've noticed my indle is at 1500rpm when cold but when it's hot or if you come off the throttle quickly It can then drop the idle to 1000rpm. I've had it stall on me before after coming off the throttle quickly and it's backfiring a bit more.
It's only been doing it recently ( since I went onto a stage 3 filter with the kev mod set at the 6 o'clock position ) ?
Could it be the good weather were having in the uk?