Jason,
How is the battle going? Verslagen has made sure everyone on the list is routying for you now, and that we are all paying attention !!!
If you timing was off (slipped a tooth when you put it back together) it would run like shite all the time, but worse the faster you went.
BTW I don't really think your timing is off right now, I think you may be fighting a petcock issue and a resulting stuck float.
The following pics show what is relatively normal depending on normal chain wear and which side of the chain guides are actually taking up the majority of the slack. If you got significantly more offset than this (a whole link's worth) then you got a slipped chain/tooth situation. Slipping a cam chain is very very rare, as is putting it in wrong is very rare
as folks are careful to check it and recheck it before buttoning up the bike.
I am also interested in hearing about your Raptor once you get it and get it put in place. You having a gas dripping K&N filter isn't normal, you know.
Stumbling/losing power at around 55 mph and up is a known vac petcock failure symptom, you know that, right? The petcock can run your float bowl almost empty and your float can get stuck at the bottom of its travel (gas stuck OPEN). This jives with your dripping K&N ....
Have you tried the trick about whacking your float bowl 2-3 times with a screw driver handle? It is a quick/easy/free way of freeing up a stuck float in the float bowl, an issue I had several times while I was fighting my own vac petcock wars back early last year. Certainly worth trying, doesn't cost any money or time ....
(whacking the bowl may need to be done at every new set of issues that you have just to eliminate the easy/free stuff)
When my Raptor went in, I did the whacks one more time to get the bike running right (float was still stuck from last set of vac petcock attacks) then I stopped having to do it as I stopped having the various vac petcock symptoms and
things just ran right from then on.
Do keep us all up to date as you fight out all these issues -- we are all interested and we are routying for you !!