I got an XJ700 a month ago and had it serviced at a local shop. The bike had been standing unused for about 3 years. Changed air filter, cleaned tank, added a fuel filter, new airfilter, oil, etc.
It ran well for the first two weeks. But now after a 10 -15 km rides it will idle at 3k - 4k and will not drop down. I blip the throttle a few times and the idlw will dropo so I can shift into first but then it races up again. What gives?
:(

I would check for vacuum leaks at the caps on top of the intake manifolds. If one of these caps are missing or cracked it will do exactly as you discribed. Ususally when the throttle stop adjustment is wrong it won't come down when you blip it, but check the choke adjustment and linkage.