Hi everyone,

I have a question regarding the EGR Control Solenoid on my 1983 Oldsmobile Ninety-Eight with the Olds 307 (bone stock — Electronic Quadrajet, SMOG equipment, etc.).

I'm experiencing issues with a rough idle (slight misfire/shaking) and little stumbling during low-throttle acceleration. I suspect the cause might be a vacuum leak at the EGR Control Solenoid — I tested it using carb cleaner and noticed an RPM change.

I have a few questions:

1. There’s a vacuum port at the back of the solenoid (under the ECM socket). Should this port be plugged? The vacuum diagram doesn’t indicate whether it should be connected to anything.
   
2. If I bypass the solenoid and connect the EGR valve directly to an assigned vacuum source on the carburetor, would that work properly?
   
3. Is there any way to find a replacement part? I checked eBay and found a few similar NOS units, but they’re priced over $200. Does anyone know the exact part number for this solenoid?
   

I've attached pictures of the solenoid for reference.

Thanks in advance!