We just bought an 07 and at cruze or light acceleration it bogs down. The plug is jet black and covered with soot. Jetting is stock. Airbox and muffler are stock.

Any ideas?

I'm no expert, and to be honest, I think you probably know more than me, but here are some basics in case you missed one:
-Have you tried adjusting the screw on the carb?
-Have you checked the position of the choke?
-Have you checked that the airbox filter and/or snorkel are not clogged up?
-The only exhaust issue I know of is it being clogged for some reason. Unless you have something like mud that entered the muffler or serious exhaust rust, I don't think the issue will be there.
-I had mine dying because the carb ran out of fuel, which just turned out to be the float in the carb not moving properly. Maybe check if the carb is flooding? If nothing else seems to fix it, I would probably do a carb rebuild if I were you.

Mostly what he said... could be several things.

Plugged air filter.

Plugged exhaust. Removing the end cap isn't the easiest thing to do. There's a screw at the bottom of the end cap that's known to be soft and easy to strip. It's much easier to just remove the tailpipe from the bike and remove the cap on a bench. Penetrating oil and heat are your friend. Once you get the screw out, the cap just pulls free but it'll probably take some encouragement to break loose.

Mixture screw way out of adjustment. This is the boss just forward of the float bowl on the bottom of the carb. There may be a brass plug covering it. The typical setting is 2.5-3 complete turn out from a very gentle bottom.

Float level way out of adjustment. The correct height is 14.1-15.1mm from the bowl face with the carb upside down.

Choke stuck on. The choke parts on the side of the carb are known to be somewhat delicate. Be gentle if you take this apart.

Diaphragm/slide not working properly... vacuum leak.

Check the valve clearances.

Ive had it apart a few times now and have noted the float level was set way to high.

Also the choke fitting to the carb is broken, could this be my fault?

That depends on what you mean by broken. Is it stuck on open, closed or somewhere inbetween?

Ive undone the cable so the choke is closed. No better. Plug is starting to foul.

Are you using the correct spark plug? I'm not sure what it should be, but maybe the temp range of the plug is wrong, or the spark might be a bit weak. (I'm really just taking random guesses at this stage)

Try removing the air filter cover and riding it. That will allow a lot more air in and should lean out the mixture.

The float level has a significant bulk effect on mixture. Generally a low float level (higher fuel level in the bowl) will result in a richer overall mixture.

If it'll start cold without any choke, it likely is very rich.

The float level is the first thing I'd address. And since you'll have it apart anyway... I'd also give it a thorough cleaning. Remove the mixture screw and squirt some carb cleaner through the passage. Then set it to 2.5-3 turns out from a gentle bottom. Be careful if you decide to remove the main jet as sometimes they're really tight and can cause the whole tube to spin, which can be a pain to correct. I believe stock jetting should be #40 pilot and #125 main.

So I found the fault. Previous owner had the carb apart, didnt refit the washer that goes above the needle.

Full floater needle anyone?

Nice find! That'll make a HUGE difference in performance.