i have one of those cheapie ebay boost controller valves on my 88TC, which is basically a controlled vacuum leak. since putting this on my cruise control surges, does this make sense that is the cause? would the Gillis valve be better and not cause this?
I have an ebay one on my car too, but no problems. Maybe you are stealing to much vacuum from the cruise control actuator. I have mine on a dedicated barb directly off the intake and I have it piped so there's no vacuum leak because I'm using a external 2 port waste-gate. I think if you give yours its own direct line to the intake manifold it will solve your problem though.