Install a wide band 02 sensor and gage - otherwise your guessing.
The AEM one works well and does not require a free air cal which makes it plug and play.
My guess is the power valve is leaking. If you turn the idle mixture screws in all the way and it still runs - the fuel has to coming from somewhere..
A lot of people think wide bands are only for tuning efi systems which is incorrect.
It will help you get the right jets in it for cruise and then drill out the PVCR to correct for WOT. Just do this one drill size at a time as its hard to go smaller.
