Chainsaw Repair

If the impulse is good then I would say you need to try a different carb.   
Did you do a pressure test of the crank case by blocking from the back of the carb and back of the muffler.
That would check the intake that way also for an air leak.  I would also do a compression test.
2 years is a good time sitting on a shelf and you never know.
I would check the muffler for any obstructions from bugs.