the puegeot 103 (gurtner 12mm) carb is pretty easily cleaned up. There isn't alot of places in it to get clogged up.. if you cleaned the filter up then you shouldn't have a problem with anything else if its running for a few mintues.
If you didn't get to the internal filter it is easy just find the big 6 point screw on the bottom side of the carb.. you dont have to even take the carb off the bike to access it.
I think your problem is simple... I would check to make sure your choke is working and that your actualy giving it long enough to warm up and run on its on before releasing it. Also if you get it running and it dies while you have the choke held in... try to reach down on the the bike and turn the adjustment screw until your able to keep it running as you let off the clutch. once you get it to stay running you can adjust it to where it runs best.