Evap Canister Purge Solenoid/Vent Solenoid

I'm hearing a faint clicking sound when I hit speeds of between roughly 45 to 55 mph.

I went a few rounds of EGR testing etc... and cleaned the entire throttle-body which got rid of the CEL DTC 0401 (insufficient EGR flow), but I still hear that faint clicking which I'm certain shouldn't be there since I've put 200K miles on this vehicle.

I need to figure this out since I don't want to eventually run into bigger problems, especially concerning my cat converters etc...

Does anyone out there have experience with either the Evap Canister Purge Solenoid (located in the engine compartment - pg 6E-608 in the shop manual) and/or the Evap Canister Vent Solenoid (located on the rear underside of the vehicle - pg 6E-605 in the shop manual)?

I'm going to take a look at the Evap Canister Purge Solenoid, since, as best I can tell, the clicking seems to be coming from under the hood, though it's hard to tell when driving.

I do have some idling issues here and there at traffic lights/stops, and once in a while it'll die when I stop, and I've dealt with those in the past via MAFs, IACs, Fuel pressure regulators etc.... I also have an issue once in a while where the idle will stick between 2 and 3K until I can come to a "complete" stop.

If anyone has experience with either of these, I'd appreciate your input.

Thanks,
Mark
Huntington Beach, Ca.