Originally Posted by corbzin,Nov 15 2009, 11:09 AM

Highly doubt its the gas, because i filled up before the storm. so im still on that tank of gas before it even started raining.

Also it s 2002..

Originally Posted by Evo9toAP2,Nov 15 2009, 01:30 AM

Your car is likely having a "brain fart". It can't resolve all the sensor inputs to make for a steady idle during certain atmospheric conditions. Many, many S2000s do this.

TRY NOT to "help" it by giving it gas when it does this. This additional TPS input will only continue to confuse the ECU even further and it will never learn. On average, it WILL learn if you just leave it alone and let it stumble and die. Then, WITHOUT touching the gas, fire it back up and let it stabilize on its own. Same goes for if it only stumbles. DON'T touch the gas till it recovers on its own. It may take several driving episodes before it learns, but since you only drive it once in a while, it may take weeks.
Additionally, long highway driving tends to make the ECU even more confused and when you finally get back into slower, city driving, the "brain fart" happens again.
You must keep in mind that this engine is a very high output, high strung one. Honda has done a great job in making it daily driveable, but there are circumstances whereby the ECU has to deal with so much information just to be able to run a little 4 banger and ring out 240 HP, that at times, something's got to give. This stumbling is one of them.

Needless to say, it is up to the owner to ensure that all parts of the engine is well maintained as even the slightest deficiency can amplify the ECU's workload. Make sure your plugs are in good condition and gapped correctly. Air filter good? Injectors get a routine dose of cleaner? 93 Octane gas can still be dirty gas if you filled up near the bottom of the gas station's tank that day or right after the tanker truck disturbed all the sediment with its fill. A few tanks like this and your filter sock will be so plugged, your fuel pressure will be unacceptable. How dirty is the inside of your throttle body area? If it's really dirty, then maybe that grunge is affecting how the MAP sensor is reading, not to mention fouling up the Idle Air Control system. Do you have too much slack in your throttle cable? How's your PCV valve? Ever changed it? So many things can add to the ECU's brain fart and make it an aneurism.
Yes, do the "MAP Whack", primarily wiggling vigorously on the wiring harness and implementing a better way to secure it (zip tie).

Try taking a flat screw driver and lightly tap on your map sensor. It's located on top of the throttle body.

This information Is on S2KCA
http://forums.s2kca.com/showthread.php?t=16066