Well my idle speed will some times drop down to around 500rpm and the car will shake for a second or two the jump back up to an idle speed of around or just under a grand. It will usally do this when i give it a rev and let it fall back down or just push the clutch in at a stop light. I was thinking it might be the plugs just needing to be changed but wasnt for sure. the car has 50k on it and was owned by an older woman before me so im sure they are the stcok plugs. Also i was wondering if anyone knew the ngk part numbers for the diffent plugs that the f20 can take.
thanks
--Arron

 

I believe that is normal. I think it has something to do with the car's ecu trying to adapt to current weather temps/conditions. I had the same drop in revs and shudder and did the "Map sensor whack" listed in this forum and it fixed the problem for me since (a year ago).

You can get the NGK's from H&A here...
http://www.handa-accessories.com/s2000-04.html

 

Its normal. My 2002 model did it and now my 2005 does it as well. Its your ecu trying to adapt. It'll stumble a couple of times. Don't try to fight it by revving the car. Just let it fix itself.

 

In my case (2001 with 75k miles), it was a dirty throttle-body. I cleaned it (I have a post about it from several months ago) and the problem disappeared completely.

For most, it's just the ECU thing I think.