idle solenoid

So I’m trying to diagnose an intermittent no idle / rough idle, truck seems to intermittently not want to idle under 1K, have to screw in the idle speed to 1200 or 1500 rpm for it to idle. Other times it will idle at 7-800 rpm fine. Went to check my idle cut solenoid, with key ignition on I hear...

Sorry if this has been asked before, my search didn’t yield any info. Does anyone know where to find a gasket for a pre-‘75 idle solenoid? Do I need to make my own? Also, I haven’t seen much on these earlier solenoids. Are replacements NLA or does someone sell them? Thanks!