[Andrew]

Get a good working actuator. My experience with the Sure Start type devices is they wouldn't hold a setting well. After you get an actuator go through the setup procedures.
Idle surge is often a sign of excess leanness. How do the plugs look? But without knowing your setup is OK you're kind of in the woods.
Andrew

 

[Andrew]

An actuator that works right will help. There are several things including rod length, actuator extension, idle port o-ring, and ignition timing that all affect idle speed.

Wes Ingram, or try Alfa Parts Exchange, sometimes they have good used. 925 200-1998. Or ask here on the BB in the parts wanted section.
Andrew

 

[Andrew]

I would recommend a systematic approach but it's in that little spider distribution block with the four hoses, on the top of the intake. Remove the large hose coming from the air cleaner. Underneath is a screw/tube, which bears on a washer on o-ring. Loosen the little clamp first. Turning the screw in should in theory compress the o-ring and reduce the idle but it often doesn't do anything.
Again, I'd go through all the steps, and without a stable actuator setting it'll be very hard to get it right.
Andrew