I'm trying to fine tune and problem solve a lumpy idle. (2.0L with Stromberg 175CT carb)

Symptoms:
Start engine and revs at only 5-600 revs for 1-2 seconds, then goes up to 1800-ish revs
As car warms up revs can get as low ar 500 when idling.
Only ever stalls within 1 second of starting, never after this.
When idles before and after being warm is 'lumpy' and shakes the car slightly. It might be ok for a few seconds then the idle changes and the car vibrates.

Things I have done:
Head gasket (and skim) - blown 4th to coolant
New distributor cap and rotor
Replaced all vacuum tubing I can see
Cleaned carb and replaced needle, jets, diaphragmetc - did it myself however
New timing chain
Idlesettings ~800-830 and 1800 (a bit faster than specification)

Any ideas why it is:
Slow to get to fast idle revs on cold start?
Idle gets very slow just before gets to full temp?
Has a lumpy idle?

Thanks for any help....