There will certain amount of engine braking no matter what speed/rpm you are in as long as the bike is in motion. So you may get fast idle at 2000rpm due to slight engine breaking which is normal. IMHO
Once I notice something off I look real deep into it. I purposely pulled in the clutch on a off ramp at 80 KM/HR at the same instant I had released my throttle , strictly used my front and some rear brake, came to a stop light that just turned green all the time on the off ramp I was at 2000 RPM, since I make a point of knowing what gear I am in, I upshifted to 4th as I was in a 60 KM/HR zone, without touching the throttle the RPM was at 2000 and pulling in 4th. I then dropped a gear and engine braked for less than 2 seconds,pulled in the clutch for 3 seconds and was at 1500 RPM. Next test was in 6th gear doing 85 KM/HR , pulled in the clutch and released the throttle at the same time, I coasted down to 65 KM/HR all at 2000 RPM with the clutch in,I blipped the throttle with the clutch still pulled in, still at 2000 RPM, to the point that I was on a major highway and doing 50 KM/HR in a 80 was asking for trouble, less than 2 seconds of engine braking reduced and remained at 1500 RPM.
The main reason for this testing was the fact that some have had a pinched throttle cable or a dry throttle cable, my conclusion is the ECU needs to see some speed reduction combined with a reduction in the TPS , otherwise it maintains a certain minimum fueling in the throttle bodies. Since others have posted similar results, ( I can't find the thread ) , my concern was also if something was sticking in my throttle bodies. Since my very last test was a gentle one, and less than 2 seconds of very light engine braking with a return to 1500 RPM, my conclusion is something to do with the ECU.
I should point out like I said earlier, this happened before my ECU was flashed, just that I never rode below 4000 RPM in 4th or higher, I now am able to ride in 6th at 50 KM /HR ( I don't make a habit of it but at 60 KM/HR I am in 6th when going through small villages , no more need to downshift , and very easy to return to 80 or 90 KM/HR without having to leave my highway pegs , thanks @Steve in Sunny Fl