Thanks for the instructions,
I'm pretty sure my kit has a speed sensor, we put this little device on the t-case speedo gear and it's connected to the ECM. Put I do get the effect that you're talking about, in a parking lot when slowing down. Mine actually idles at 1000 rpm. With the carb, the best we could get was around 800. We'll try the IAC procedure.
What's this IAC tool you're talking about?