People 50 - not running

[widespace]

2011 People 50 - I bought it with 200 KM this year,  after being garaged most of 3 yrs - and today has 5000 km.
I mentioned some performance hiccup's showed up @3000 km here - http://www.kymcoforum.com/index.php?topic=12558.0
I changed out the fuel filter,  checked spark plug which seemed fine - minor grey film only - checked air filter, very clean.
I next used a few tanks of fuel system cleaner ( Gumout) -- and the bike ran good enough for another 1500 KM or so. Once and a while would still hiccup.

Then I started getting big hiccups - failing outright at full speed (about 40 mph, highway travel on this bike) .. Just loosing power, then dies within 1 minute
Checked fuel flow, tapped the carb,  after about 20 minutes it fired back up and operated w/ no problems for another 40-50 miles
This happened another couple times and at last point it was running,  not more than 2-3 miles without dropping power, then failing. Always started without hesitation.

So I resolve to cut my teeth taking apart the carburetor and cleaning it. Zombie sent me some Youtube clips that explained what was involved, pretty good. I got through that! - not a big deal really.  As I am not surprised to find - there was very little build up in carb. Jets were clean. All throats and bowl were pretty clear.  The bike only has about 5000 KM on it. Cleaned the air filter while I was at. 

Put it all back together,  and here's what I got:
Idle came up just a little irregular.  Okay, I take it out to see how it rides. It rolls, accelerates normally, reaches full speed - for about 1 mile. The power slowly fell off, giving it throttle all I can travel is up to 20 mph, then 15, then 10..   and I'm coasting, pretty sure I can hear it is still idling -- but finally dies. I roll bike to garage, and next - it will not turn over. 

Mechanic friend keeps telling me there could have been some bad gas, that the fuel cock or tank could be clogged with debris.
So, I pull the line after the fuel cock,  before the fuel filter, turn throttle -  and get a healthy squirt of gas. This tells me there is not a problem with gas flow from tank,  through fuel cock. Fuel filter is new, not dirty.

What I'm thinking is that if I put the carb back together wrong (first time I've ever tore down a carb, I could have missed something putting it back together) the bike would not have run. But it idled (though rough) for 5 minutes, then I had full throttle and top speed - for about 1 mile.

What should I check? 

[zombie]

Too many things to list... It could be a bad or going bad CDI/Stator. They will often fail as they heat up.
Do you have a multi meter, and a service manual for the bike?
 There is a manual here in the sticky called Kymco links. half way down the second page.

It could also be a leaking vacuum line or cracked/loose intake manifold.

if it starts again ride till it dies, and check immediately for spark. Just a wire from the cap is good enough for this. Hold it near metal, and see if you have anything while cranking.

I does sound electrical to me.

[BettinANDlosing]

Did you ever physically clean the carb when you got it? Could be plugged. Also did you replace the stock filter with another stock or remove the paper and add an inline filter? The stock filter on the p50 is for heating up and not flowing fuel. Just fine suggestions, and you should make s habit of changing your plug around every 1000km out less regardless of how it looks.

[widespace]

GOOD NEWS - back on the road -
It was the plug!  That simple~ Zombie was right, electrical. 
Here's what I think: last look at the plug was before using the Gumout. That Gumout really cleaned fuel system up.. and the junk burned off totally fouling the plug.  I'll bring a picture later ..  Sheesh ..   a huge cake of debris and no gap . After cake of debris cleaned away, it could be seen the element was nearly melted gone. I would never have thought that much degradation could happen in a few miles .. probably all the junk that was clearing away with the Gumout.
BettinANDLOOSing, I'll take your advise and just change them out from now on, every 1000 or so..
BettinANDLOOSing,I'm going to get back here with pictures of the fuel filter I replaced. It wasn't paper, I want to be sure I know what you're talking about. 
One  more : Where is this Kymco links sticky?  Cannot find ..

[BettinANDlosing]

Did you replace the filter inside of the little black plastic "bowl" or snip the fuel line and put one "in-line"? Also ANY fuel additives you use will shorten the life of the spark plug, and poor quality two stroke oil will DRASTICALLY shorten the life. The good stuff is expensive, $15+ but worth it on your 2t machine. Always use full synthetic.