I have twin 540's with 1050 Holley Dominator's. When cold starting, the starboard engine runs perfect but the port engine needs to be throttled for a while (until it warms up) or it will stall. It is not a big deal but was wondering if this could be adjusted, after it warms up all is good.

My twin had the same problem years ago. Turned out to be the distributer. The advance was bouncing , You could see it with a timing light. At idle one motor was steady and the other bouncing.

Maybe lean?

Do you mean lean, like idle mixture?
I don't know much about the Holley's.

when you restart it do you get a plume of black smoke and soot out the exhuast or is it clear ? if it's sooty the idle mixture is too rich if not it may be too lean. check the timing and all the other basics too. and like dave said make sure the timing is holding still at idle. It may also be ideling a little low, if you have a good digitail timing light with a tach check idle speed, it realy shouldn't be done with the boats tach.

Usually I get the black smoke cloud from both when I restart it. If I lean out the mixture screws, it wants to stall when I put it in gear or at least idles real low , even if the idle is at 850 when in neutral.