I have 02 s2000 and I have this idle issue I am not sure if its normal or not.
When I rev it up to like 2000 in neutral when the idle drops, it drops really low the car makes vibration sometimes almost like it was going to die. I found it more noticable in the morning right after the car warms up. I replaced map sensor thinking it might have something to do with it but still seems the same.
Can you help me figur this one out? Thanks .

 

normal. it might even stall when theres a big temperature change when you last drove the car.
it's the ECU learning it's idle setting.

 

Sounds like a DIY....it's called a MAP WHACK. No, seriously.

https://www.s2ki.com/search/forums?query=map+whack

 

And clean the idle air control valve. It's also in the DIY/FAQ. If you're in Indiana I'll do it for you if you bring it over