Backstrom

Hi all!
Need some help to get my idle sorted out. Have tried everything i can think of, engine still "shakes" about every 5-7 seconds, then smoothes out. Doesn't respond very much on idle mixture screws. If screwed in the engine stalls totally, but outward does'nt make much difference.

Build:
461
9,85:1 cr
Edelbrock heads (ootb)
performer intake
qjet 800
Msd ready to run, timing 34* total all in by 3000, initial 13*,vacuum disconnected.
custom grind Comp roller, 234-238@.050, lift close to .600, 112*lsa, 107*icl
vacuum @ idle (800-850) around 15 in/hg
Manual trans, 3,07:1, 442 convertible '69

Have tried manifold vacuum too, but didn't like it.
Carb was completely overhauled by a well known rebuilder over here in Sweden, and has a modified idle circuit for bigger camshaft. I have tried to contact him but can't get in touch with him.
Since this is a '77 Olds 350 carb, (17057253) I suspect it to be a tad too lean for my build, jet/rod combo is 73/48k. It has adjustable APT, but can't notice much of a difference adjusting it.
I remember the builder said to try stock jetting to begin with, and it worked quite good on the near stock 455, but after the changes it has started this behaviour, and after going through everything else such as timing and vacuum, this is what remains.
What do I do to begin with?

Thanks /Anders