So one of the members of my group has a 2008 ZX14 and it suddenly started to idle at 1800-2000 rpm. He could manually get the speed to drop by rotating the throttle forward but it would immediately go back up

After several false starts, I suggested that maybe the IAT (inlet air temperature) sensor had gone bad and was telling the ECU that the engine was constantly cold. He pulled the sensor and found it had some oil on it. I think from over oiling his filter. He cleared everything off and put it back in and the idle has returned to normal.

Hope this helps someone

Mad

Good diagnosis! He might be getting oil in the airbox from overservicing the engine oil too. My 08 would do that. There's no reason to wipe it out. Every bit runs back eventually and there's not so much as film left but obviously one needs to stop overservicing the engine oil.

Back in the day my friend had a K&N. His throttle stuck open one day. It turned out to be something similar, the filter oil had dripped onto the throttle linkage and gummed it up.