Idle Boost Solenoid

My 90 Accord began missing at idle about a week ago. The a couple of days ago while parked at idle I could hear a clicking noise under the hood. I determined that the Idle Boost Solenoid on the firewall was clicking (I could feel it with my hand as well) and each time the engine would stumble. Now the engine is missing at all speed and performance is terrible. Do you guys think the solenoid is bad or should I be looking further?

Engine idle control valve on the firewall. The EGR valve solenoid is on the firewall. To control idle, I think it is the EACV located on the intake manifold. Tell me more.

Is the EGR solenoid the one that has the vacuum hose running down to the rear engine mount? That is the device that is clicking. Every day the car runs worse and I hear the clicking from that solenoid.

The EGR solenoid is located in a plastic covered enclosure on the passenger side firewall. It takes vacuum from the manifold on hose no 16 then goes to a constant air regulator, solenoid then connects to the EGR valve on the intake engine near the top hose to the radiator. For the hose that goes down toward the rear motor mount, where does the other end go. Are you sure it is on the vacuum circuit or is it on the fuel circuit? Can you take a picture of the solenoid?