What are the main culprits? Carb too rich/float too high? Valve timing? Engine timing? Dirty plugs? I'm about to tune-up a 1965 era /6, and want to pay particular attention to the emissions, simply because I want it to burn fairly clean. It had points, now just installed Pertronix ignition. Other than that it is all stock. She starts right up, runs rough for 5 min, then runs smoothly. No smoke.

_________________
Never seen a Valiant I didn't like!

Any/all of the above, yes. Tune-up parts and technique suggestions in this thread. Also don't forget the engine requires periodic valve adjustment. Carburetor operation and repair manuals (and some training movies) are posted here for free download.
Rough running for 5 minutes suggests choke problems. Welcome on the board! You'll want to pick up these three books as quickly as you're able; they'll get you rapidly and widely up to speed on how your car was built and why it was built that way, how its parts work, and how to service it.

Information on making the current-production plastic PCV valve work with the pre-1966 chimney/cup style PCV provision here.

Your cold-engine stalling issue is choke- and/or carburetor-related. You may decide to install one of the electric choke kits if your present choke thermostat is old, and your carburetor's choke pull-off may need adjusting. Carburetor information is here, and choke information is here.

You may also want to do the fuel line mod.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks Dan! This web site is fantastic, and so are you!

_________________
Never seen a Valiant I didn't like!