If the muffler spark arrester isn't clogged and the compression is at 90 psi with the throttle held open then my experience says the engine is worn out as for here it takes at least 100+ PSI for a handheld two cycle to even hit,alone run.
I actually shoot a for minimum of 110 psi.

I have had only a couple over the 10 yrs I been repairing two cycle handheld that would run at 90 psi.