Yes, so I built a home made throttle stop using a bimba two way cylinder, two Humphfrey solenoids and a adjustable needle valve on the exhaust
Side of one solenoid.
This uses pressure to both close and open the throttle stop by using a needle valve on the exhaust port of the closing solenoid I can slow down the opening rate.
If you rely on a spring to close The throttle when the stop is on you can get erratic closing rates and if you use a restriction such as a needle valve on the pressure line you can get erratic opening rates as well.
I assume you know the. Importance of having a rock solid pedal stop for this type of throttle stop.
You can try just lubing the throttle shafts in the carb with WD 40 but it's a temporary solution only.
If you have any questions you can e mail me @
greatbaer@sbcglobal.net
Note I do not manufacture or sell throttle stops but I will assist you if you want to build a better one.