plug the vacuum advance into a manifold source. let it idle at 30 or 35 degrees.
then turn down the idle screw to lower the rpms to 950. (More timing will raise the rpms)
try readjusting the mixture screws for best idle. they should be working now with all that timing and more closed throttle blades.
check the vacuum. should be making more than 12 inhg. I would think that cam should pull 14 or 15 inhg.
try a new power valve. a size 5 would be better
make sure the float level is set right.
blow out the idl air bleeds with compressed air.