problem is your fast idle thermostat valve is shot..
To diagnose and confirm:
Take your intake off(should be simple 30 sec removal!).. Then while idling, look up inside the throttle body and listen.. Loud whistling? If so, signs are getting stronger.. Next, look inside the throttle body and try to locat the HOLE on the lower part of it.. Its about 1/3 the way up the cylinder towards the rear of the throttle body.. Once you look up inside, you'll know what I mean.. You should have 2, one low and one high.. The holes are about the width of your pinky finger(i.e. the little finger)... Now, cover that whole with your finger and see if it feels like there is a sucking on it.. Does it? If yes, then you also noticed a serious issue.. your idle went back to normal... This is good... Basically, it confirms a common issue with the H series motors... Sadly, its not well known, and there are several ways to fix it..
Your car specifically: It revs up and down from 1-2k in a fixed pattern... To me, I would be willing to bet thats the issue, especially since you said the intake has a loud sucking noise.
Causes: Well, the fast idle thermostat valve often goes bad for a various number of reasons.. Basically, upon warming it stays a little ways open due to the design which is really neat. There is a rubber screw in it that is beveled.. When the car is cold, coolant flows through the valve and the screw is able to basically unscrew so far. By doing this it allows a hole in the intake manifold just like a vaccuum hose ot open and suck in more air into the intake. This is used to SAFELY(as deemed by honda) warm up the car at a higher idle. As the coolant temperature and car temperature increases the screw expands as it is made out of rubber.. Thus, it screws in allowing no air to flow from the intake mainfold to the intake itself.. Thus, lowering the idle and allowing the throttle to operate correctly... Now that we know how it works, I bet you can see what can go wrong.. Old cars such as ours can have deposits form in the radiator made out of whatever.. These flow through the coolant lines and can block up things.. Maybe this caused your problem, or it could be one of many various other reasons...
Solution: It all depends on how permanent you want your solution to be.. Temporarily, you can cover that whole with a piece of duct tape... I have before, but it doesnt make a permanent solution and can present an issue going into the intake manifold, so make sure you place it well.. Even if it gets into the IM it wont make it too much farther and it has potential to get burned up or cause valve damage, but I wouldtn worry about it... This is only temporary and you plan on placing it well anyways right?
Long term fix: 1)replace the unit 2)clean the unit and reattach until problem goes away. 3) Leave it as it is cool to rev at everyone all the time while idling.. (Personally, I like #3.. people wanna race ya..
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Where is the fast idle thermostat valve:? Its located on the underside of the throttle body.. Its easiest to get at by removing the for nuts the hold the throttle body to the intake manifold, unhooking the coolant lines to the fast idle thermostat valve, and the TPS and removing the throttle body.. Once you have this out, you can easily access that underneath metal piece... You have to undue two long bolts which hold it to throttle body.. Be CAREFUL of the gaskets!!
COST of new one: about $80 with tax from Honda...
Any more questions? Ill post pictures if you really need it, but it wont be for a while as my camera is on loan... Time factor also comes into play..
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