Anyways, I own a 99 Civic Si, 46,000 miles on the odo. I'm actually thinking about paying the 350.00 and get the 60,000 miles tune up done early. Well, yesterday when I was pulling her in the garage, I noticed that there is a pretty audible rythmic clicking or actually it sound almost like clanking, sounds almost like the olld diesel benzes. I revved her up and the clicking sound goes away, and all I hear is the normal valvetrain sound spining up, but when at idle, the sound comes back. Also, after some revving when I let her go back to idle speed, it tends to drop below normal idle speed and almost stall, this happened maybe twice out of the 15 times I did it. I have a toda flywheel and clutch, the weather in Houston has been cooler than norm lately, and my friends were telling me that the idle could be a little messed up due the colder weather and the ECU has not adjusted itself yet, I'm not to sure about that. I've had the flywheel on for over 20,000 miles and even when i first got the flywheel on, it never made that sound but it did want to stall at first. There is no loss of power of hesitation when at WOT, actually, it doesn't seem like anything is wrong with the motor in terms of power and performance, just the weird sound. Sorry if this question has been brought up before, but just a bit concerened. Am I just being paranoid and worrying for nothing or is there something wrong? Any input on this would be great.