Engine & Internal - idle is loud & goes up & down--a problem??

When I get home from work or get to work after about a 30-minute drive on the highway, I'll pull into my spot, and if I just sit there for a minute, the tach needle will rev up and down, and a lot higher than it used to. It's pretty loud and the needle doesn't just move a little--it really goes UP and DOWN. I'm totally guessing here, but maybe like 150-200 RPM from low to high and down again. Is something not right here? If so, what might it be? Thanks.

Search: Idle Surge Issues

Its a thread I started when I was going through the same thing. Tons of troubleshooting info there.

Good luck!

Idle Air Control Valve (IACV).

Unbolt it, clean the screen, and enjoy your nice idle.

http://www.hondacivicforum.com/m_569518/mpage_1/key_/tm.htm#569518

thats not my case i have done that i found out its my FIV its cloged and its stuck open when i plug the lower port it stops im going to clean it when it gets light out and then let everyone know if that fixed it

i have the same problem...also heard it is the throttle posistion sensor....i will try cleanin the idle crontrol valve, id love to enjoy a smooth idle....

My idle was doing the same thing a few days ago. Shortly after, I had disconnected the battery to change the fuel filter. Ever since then, the idle surge has been gone. I guess resetting the ECU (if that's what happened) did the trick. Not saying that's your problem. Just saying... lol

Good luck, man.