As above looking for some help. My missus bike is a 2003 pro 200 running a Dellorto phbl26 carb. Having many running issues. The bike often just stalls once returned to tick over I've turned the screw up to prevent this and it idles much quicker than Normal but still randomly dies. The biggest issue for her is that you must have throttle on to ride even on flat concrete you can't pop it in first and let it roll on Tick over it just lurches about and stops. I've tried playing with the carb but I'll be honest I don't know what I'm doing any help would be much appreciated as she is forever having to restart the bike and it's taking all the joy out of the bike thanks Mike

Biggest thing is a clean carb. Second thing would be a 9 tooth counter shaft sprocket to make it easy as possible!

What you need to do first is make sure the rest of the carburettor is clean inside, you need to remove it from the bike, take the 14mm brass nut out from underneath and remove the float bowl, line everything up on the bench in order and remove the pilot jat and starter jat. blow them out with compressed air and refit back together... By the sounds of it I bet the pilot jet is blocked!!
With the fuel screw (the one to the left of the idle screw) turn it all the way in, then back it out 3.5 turns, this is a good base setting but all bikes run differant.
With the tickover screw you need to just start the bike up and turn it in until the bike is just ticking over nicely or where you like it, if the bike is running lumpy (rich) then just turn the fuel screw in a quarter of a turn at a time until it runs better. If the bike is hunting for fuel (weak) then turn the fuel screw out until it runs better...

Hope this helps copied this to save typing 

In addition to cleaning the carb, check the o ring on the bottom of the choke (item 30 in this diagram) is in good condition. When I bought my 2003 200 it ran similar to yours. I stripped the carb and blew out the jets also finding the o ring had gone. This was replaced and the carb rebuilt it then ran fine.

http://www.ducatimeccanica.com/dellorto_diagrams/phbh-l_parts_list.htm

Update: so I managed to get it stripped down and cleaned this afternoon. I did find that the main pilot jet was partially blocked 2 of the 4 little holes on the side. Also as you quite rightly say that exact o ring was slightly damaged so I replaced it. Rebuilt and fitted back to carb set it at 3.5 turns out. To my untrained ear it seems to run well at 3 and a quarter turns out and revs up very well in the garage the true test will be to get it out for a test run.

Same accounts for the o ring inside the fuel screw. Somethimes people take it out, forget the o ring, and blow it with air. Bye bye o ring. Its there for a reason.