Normal idle speed for GLi is 800 rpm. I owned a GLi with this same problem. I had learnt to modulate the throttle when setting off and with time it became muscle memory so it did not bother me. What bothered me was the low idle and occasional idle dip. Everything worked top notch, but this problem still persisted.
In my case, the previous owner had used this car on cng, and later removed the setup. Because of the cng kit, there was definitely a leak in the intake manifold, intake pipe or TB somewhere. I never got it checked, but I figured the low idle was because of the extra vacuum in the intake.
You probably have a crack in your intake system. Get it checked.
