Just bought my old Pan back after an absence on 4 years or so - good times!

Trouble is, I can't get it to run - bad times!!

After a bit of a clean up and a once over, i got it started no problems (fist time!!

) and let it run for a bit. A little later I decided to take it for a spin, that's when the problems started.
It started straight up straight off on about the second or thrid kick, so all seemed well; but it didn't sound right and was struggling to hold for about 1/2 mile when it finally gave up the ghost and cut out - in the middle of the local rush hour!!

After a lot of kicking over and the odd splutter to life and 20 yd trundle, I gave up and pushed it the 1/2 mile home - through the rush hour....

That was yesterday.
Today, i had a blitz and did the following:
Checked plugs - gap good slight sooting on the tops (rich mixture?)
Checked in line fuel filter - half full of cr@p.
Checked gap on points in distributor - seemed a little wide so brought back down to HD recommended gap (4/1000" - 6/1000"), until i realised that this was the later model of ignition system; hadn't recorded the original gap and spent a while playing with gaps.
Checked the carb - reset the idle speed, mixture and pump adjustment screws to the 'stock' settings, then spent the rest of the afternoon playing with these settings and the points gap.
Bugger me (old English saying) if i could get it to start really sweet of the first kick or so, but then it would die out after 10 - 15 seconds.
So what do i look to:
Carb Bowl (S&S Super E) - give it a clean out? But if the filter picked up all the cr@p, surely the carb will be clean?
Replace the petcock? Gas tank is @ 1/2 full but i seem to get different results between 'on' and 'res'.
Re-position the points (automatic advance system) - what should be the gap? i ended up with around 12/1000" and it sounded fine; the assumption is that the timing is good, but then again....oh no, I'd rather not think about getting into all that!
Any suggestions guys?
SF