2002 Honda CRV loosing RPM, power, rough idle

Boy I hope you may be able to help with a problem I am having with my honda crv 2002-ex.

1)-rough idle. Fine when cold but as the vehicle warms up it starts to shake, worse with a/c on. Idling at between 400-500 rpms according to tack on dash.
2) On highway it runs good as long as you are accelerating. At highway speed it starts to shake again as you back off the gas pedal. You know how once you have reached the speed you want to stay at-you generally will rest your foot on the pedal. I can take my foot off the pedal reaply and the suv runs smooth. Something I notice is the rpm level drops by a couple hundred when it starts to shake. It usually runs about 2800-2900 at 60mph. As it starts to shake it drops down anywhere to 2400-2500 rpms.

Any ideas at all.? This started after driving up a long hill and back down when the vehicle was nearly on empty. I thought it was a dirty fuel injector but appears to be fine. Also sommetimes when idling in the yard you can smell unburnt gas.

Could this be because the base idle is a bit too low? What do most crv's idle at. This is my 4th honda and most others I have had would idle a bit higher closer to 650-750 rpms. It seems to be dropping in idle rpms all the time. Throttle body maybe.

Any advice would be greatly appreciated. I have a friend who also has an accord and we seem to be experiencing the same problems. Odd.