Pull the airbox off and have a look at the carb slides. Are they 3/4 ot fully open? Maybe a bad throttle cable. Check operation of carb slides via accelerater.

Also, how old is battery? NSR's are a pain to start with bad battery, may explain erratic idle.
When was last time you cleaned carbs out? If never/over 6 monthes, do that while inspecting slides.

Thats my 'relatively new to 2-strokes" guess.

Hope this helps...
_________________
........."I love the smell of 2-stoke in the morning.......Smells like victory"............

MC21 Pentax SP...... TYGA'D