Is it on the back of the intake manifold? If so, that's the IACV - idle air control valve. It has coolant running thru it and it's supposed to let the engine idle higher when it's cold so that it warms up faster. Then, when coolant temp is up to normal operating temp, the IACV lets idle drop to whatever the idle adjuster screw is set at. If you have air in your cooling system, or if the IACV is just plain bad, your idle will fluctuate. I have a spare IACV if you need one. It's off a 98 JDM ITR, but it'll fit your 96 Integra since it's the same part number. I bought it when I thought my IACV was bad, but it turned out to be a vacuum hose that blew off under boost. Let me know if you need it. It's $188.57 from the dealer, $150.86 online from http://www.acuraautomotiveparts.net , $60 from me.