All that pin on the stock ecu is a signal from the reed switch on the back of the speedo that triggers when you hit 180km or whatever it is. Its not an output.
If its hunting, rip the cold start idle up off from under the throttle body and clean it and the water lines as they commonly fill up with gunk/rust which causes the hunting,
^ this. Even if you've numbered them it'll pay to check the clearances. Its worth the hour or so work to do it and get the shims right especially if you've gone to all that effort