Things were going ok after I rejetted and did my spacer mod, although I suspected it was running rich in mid range, so I took the slide back out and lo and behold, I put the washers in the wrong place (under the c-clip)! So I put them where they belong and added one for a total of 3. Now the bike will start, idle normally for a few minutes, then begins to die unless I hit the throttle. It will ride roughly in 1st and 2nd, but dies immediately upon shifting into 3rd. Any thoughts? Maybe the needle is jammed up? Would this affect the idle circuit? Thanks in advance.

Replace the petcock with a Raptor unit.

Ah yes, the good old petcork.  It's that insidious item that will mimic symptoms of issues with other parts and make you pull your hair out.  That stupid piece of junk wasted all sorts of time and effort on my 2003.  Besides, the poor design, I think mine wasn't screwed together tightly from the factory.  One of the first things I did with my 2012 last fall was to install the Raptor unit.