Megasquirt EFI Lean Cruise Reality Check

Hey everyone,

I am having a hard time getting my tune dialed in for lean cruise, and I wanted to see if anyone has a reality check on me. WOT performance is fantastic, this is specifically only a problem for highway cruising.

The car is a 340 Duster, 4 speed, 3.91s. The 340 is a pretty vanilla build - XE274 cam, 9.5-1, Edelbrock closed chamber heads with some squish. Pulls about 13-14" of vac at idle. Cruising RPM is 3-3.8k.

The ignition map is pretty close to how a distributor would be dialed in. 12-14 initial, 12 "Vac advance" at 70kPa in the manifold (9" vac), and 22 mechanical advance by 3000 RPM (34-36 total). The timing is accurate, and I have set the timing offset in tunerstudio - I am confident there isn't a mistake there. I don't have decel fuel cut on. I really think it's in the fuel and ignition tables.

Here's my dilemma: My cruise AFR is around 14-14.5, as I like to be on the richer side of things as I do the tuning. But as I add more advance at cruise (any more than 38 or so), the engine hates it. I get light pops out the exhaust, and pops on decel. I have pulled all of the low load advance past 3k, so anything over that is a fixed 36 degrees of advance. I was fully expecting to need 40-50 at light cruise, and the fact that I can't get there is leading me to believe the fuel tune is keeping me from getting there.

Now, I am thinking I may be too rich to run any more advance, so I am planning on going up in AFR, then readjusting timing, and repeating the process until I can get a nice lean cruising AFR and a rational advance. Then again, this is the only car I've ever tuned, so I am missing some reality checks (i.e. that cam doesn't want that much cruise advance, too much rear gear, etc.)

Can anyone with similar experiences getting this all dialed in give me a reality check here?

Thanks!