Most of the time, when I start my car, the rpm would jump right up to 1750 rpm and start warming up from there. Random times, it would only jump to 1250 rpm or right below 1500 rpm and would kinda bog between that range and after 10-30 secs., it will jump to 1750rpm and start warming up as usual. Sometimes it would be below 1000 rpm and after couple secs, it go jump pass 1500 rpm and start warming up. This happens at any time, whether my engine was started first time of the day, at night, daytime, even after couple hours of driving. It just happens like 1/10 times or so. I'm running a 00' B16a2, I already changed out my oil, oil/fuel filters, spark plugs, distributor rotor, and air filter. Distributor cap is still good and throttle body was cleaned. I have no modifcations other than a test pipe and 2.25" mandrel bent piping. If anyone has any idea what could be the problem, please post your thoughts. Only thing I could think of is the IACV (but my idle doesn't jump) or charcoal canister. Sorry for the long post.