most probably it is TPS.
hook on tuneecu, and adjust it to .60 V warm engine.
if it is less - e.g. less than .56V warm you get that behavior, for sure.
I had .46 warm, and 4500 - 5000 RPM idle, veeery nice in town...
removing air box:
if you have original airbox and torx screw to fix TPS - well well...
read earlier posts about that;
I have hexagon screw and ITG foam filter (I warmly recommend it, it is just fantastic!); so plenty of room to adjust TPS.
btw, basic EU 2008 Akramap (O2 on, SAI off, EPC off) for this setup:
2*Leo Vinces with baffles + ITG foam filter.
Perfect driving experience, power from 2500 RPM, torques 6 gear in 3000 RPM cruisin', MPG 47 best, 44 aver. !!! I'm happy to have this great beast to carry me to horizon!