engine breaking up at low end

Oh, gawd; just like my 340 gremlin. Won't idle under 20 Degrees at 800 rpm. 30 vac. At 30 degrees, better; 20 vac.
The cam seems to be purple, or close.
Centered.
I think this is what the engine want's; Gonna try to pull mech advance down in the dist. Oh, I tried normal timing light, and an advanced; difference of 10 degrees; don't trust either of them.