Trouble with new Megasquirt (fuel or wideband most likely problem child)

[whodwho]

...you can't *really* run pure Alpha-N with an idle valve. As the idle valve moves, engine load changes, but since the ECU doesn't 'see' the TPS load change...

Good call I had forgotten about that, it has been a few years since I ran my ITBs and I was setting it up for boost and only ran Alpha-N very briefly to get them up and running before changing over to ITB mode so I didn't fight that battle.

[Austrianvespaguy]

Yeah that's fine, and you can certainly run just alpha-n while 'running,' it's just tuning idle together with the idle valve that gets tricky!

[digger]

Ok, here's my first observations/suggestions. I think you ARE indeed going lean. AFR starts creeping up just as soon as afterstart enrichment goes away, and your VE is in the low 30s, which I certainly don't consider 'high' for an M20:
Next, DISABLE closed-loop idle and EGO feedback. At least for now/while tuning, you want as few variables as possible to simplify things first. Add the fancy features back in for FINE tuning once you get this close on open-loop.
Thirdly, you can't *really* run pure Alpha-N with an idle valve. As the idle valve moves, engine load changes, but since the ECU doesn't 'see' the TPS load change, it keeps fuel the same. You can see this as the abrupt drop in AFR right when you idle valve closes down some, while PW stays constant @ 4.4ms. You can sorta fudge around this by carefully compensating warmup enrichment against your idle valve position, but the 'right' way to do it is to change from Alpha-N to ITB mode.
ITB mode uses a 'blend' of TPS and MAP signals for load, but it involves a bit of work to set up the ITB Load Settings curves and redoing your VE table accordingly. Will give you the best result in the end though, so I'd recommend it.

One way to use AN is just add a fuel compensation table so when the IAC moves it adds or subtracts fuel, this also helps limit the cold start enrichments that get built into that table because the ECU doesn't know the load is changing as IAC opens up to create the fast idle when cold. Its not perfect but helps alot.