Idle rough when cold, ok when warmed up.

 

GeorgN10,

If you're experiencing rough idle when your Accord is cold then I would hasten to guess that either your spark plugs or ignition wires are worn, or that you have a vacuum leak somewhere along the intake manifold/throttle body. Try tightening up all of the clamps around the vacuum pipes to ensure that there is minimal tolerances in the piping fit. Perhaps your intake manifold gasket may even be worn and consequently is causing a rough idle (the intake manifold is ref #11 in this diagram: Part Detail

If everything checks out okay with the ignition wires/plugs as well as the vacuum piping then I would inspect your EGR valve. It could be on its way out and, as a result, it's causing your Accord to idle roughly when the engine is cold.

 

Thanks for your useful information.