I'm at about 20-22° at idle. 37-39° at 2k rpm. Ifr's are in the high position. Upper corners of the metering blocks. The condition will occur even coming to a stop rather gradually. I run a reverse manual valve body.. if I'm in high gear approaching a stop and down shift to second just before it trys to stumble, the rpm increse will mitigate the stumble if I slow down gradually enough. The gauge will still flutter towards 15-16.. but the car won't stall.

You need to move them [IFR] down to keep them covered in fuel. They may need to fattened up a bit especially with e85.

I've fattened them up to the largest IFR's I could find. It's a purpose built E85 carb, it came with size 46 IFR's factory. I now have size 59's installed which are the largest available in the kit I bought. Is there a brand of metering block you know of that has the IFR location located at the bottom ?

You don’t need new metering blocks. Drill and tap the lower position and use brass set screws from McMaster-Carr or similar and drill your own jets.

Yep it's easy lots of videos out there. The screws are 6/32. Drill slow with some oil.

I use a pin vice to drill my brass set screws, #6, #8, #10 or larger
No oil though, just hand pressure pressing and slow hand rotation speeds

Ok, I'll move forward with relocating them. Hopefully this does the trick. I'll post the results. Thanks for the input all.

a word of caution when drilling brass set screws, or enlarging holes that are already there. this applies to all methods, drill motor, drill press, or hand operated pin vise.
watch the "break through" at the end of the hole. this is where the majority of broken drills happen, because the flutes of the drills stick on the last couple of fines. this happens whether using lube or not, and is just the nature of the material.
it is also a good idea to replace the bit size often, so you have a sharp cutting edge.
most think brass is a soft material [and it relatively is], however, it is abrasive, and requires the sharpest tools you can use to successfully cut, machine, or drill it.
just speaking from a 45+yr working career as a machinist, [and still practicing] with lots of scrapped brass and tooling under my belt.

had this same issue, before you go nuts with drills and modifications try dropping your timing to 8 or 10 btdc and open up your primary throttle blades, turn your idle screw in.

Welp, after screwing with this carb for months dealing with this condition, I've just decided to cut my losses. Switch back to gas and put
my trusty Holley 9380 850 double Pumper back on. I tested it today.No more stumble while rolling to a stop !! HALLELUJAH!! .. Perhaps relocating the IFR's down low would have fixed it?.. but still , I didnt wanna go drilling away on the carb based on what is still just a guess in my opinion.
Wanted to say thanks to anyone who gave feed back or offered input. I'm gonna sell the carb, hopefully the guy who buys it can tune an E85 carb better than me.