Was it not doing that before the ECU change? Did you change anything else while you were at it? Like Mike Gerber
said, hot idle rpm is controlled by ECU and is non-adjustable (cold idle IS adjustable on the TB).
I have a similar problem, if you can call it that: the car idles at 680-700 in Park/Neutral, and drops to 640-650 in gear. Toyota states your idle RPM should be 750+/-50, so technically 700 is still ok.
In my case, I cleaned throttle body to no effect, cleaned EGR and replaced EGR modulator, Seafoamed the engine. None had any effect.
Then I changed my engine mounts with OEM units, and vibration became barely noticeable, and only when in gear. This was the best "fix" for the vibration issue.
I also changed my thermostat w/ OEM one, and this helped somewhat, as before the car could drop to 610-625 rpm while in gear.
The only other thing I would try is to check the engine coolant temp (ECT) sensor.
Hope this helps.