My car did the same thing, idled up and down when it was warm. It turned out to be the part of the throttle body that makes the car idle up so it can warm up faster was jammed open. Do this to test it: pull off the intake tube and look at the throttle body. There should be two holes before the throttle plate, towards the firewall. Cover one hole up at a time until the idle stabilizes. If it does, you have found the culprit. If it idles when the top hole is covered, then it is the Idle Air Control (IAC). Bottom hole = Fast Idle Thermo Valve. If it doesn't do anything, then you're screwed. j/k. If it still doesn't idle, look at the throttle plate to see if it is stuck open a little bit. Or you can get some quick starting spray and spray it around the intake manifold while the car is running. If it idles up a little, then you know the general area of an air leak. Good luck, idles can be a bitch.
Oh yeah, if you have never removed your Throttle Position Sensor before, then I wouldn't worry about it, Honda sets those perfect at the factory.