Quote:seemed like the throttle revved up for a second or two and then returned to normal? Does that make sense?
Make sure the twisgrip closes all the way when you let go of it. You can do this with the bike in neutral. Open the throttle about half way and just let go. Engine should go right back to idle. If it dosen't, check the throttle cable adjustment.
Another possibility is a sticky slide in the carb but you said you looked at that.
If the throttle is ok check the clutch cable. Make sure you have a little slack in the cable. When you pull the lever it should move a little - a quarter of an inch or so - before it gets tight and actually starts to move the cable. If the cable is too tight the clutch will slip causing the symptom I think you're describing.
On decent pavement your front end shouldn't wobble at 50mph. How is your front tire? Also check the air pressure in BOTH tires. 29psi front,33 rear is the factory spec. for a solo rider. Start with that.