Engine RPM increases when brake applied??

I have a 99 Ranger, 4 x 4, 4.0 V6 with auto trans. The problem is intermittent and can happen when the engine is cold (just started) or after driving for a while. I'm coming up to a stop sign and apply my brakes and engine RPMS begin to increase up to 3k when it cuts out and drops back to an idle.

I have had it happen when I was using cruise control, as well as when I know the cruise had not been turned on.

As I said this is intermittent and I never know when it's going to happen.

thanks.
dwh