Here is a pic of the metering lever side. You need to remove the lever/spring/needle and hold it up to a light. Then blow that passage out
with some carb spray, and hold it up to a light again, and visually verify
that the passage is clear..
Also you might remove the small jet with a small flat screwdriver, and blow it all out, then reassemble.
90% of all of these problems are carb/fuel related, and a little scum/varnish
in the carb can cause lots of trouble.
As far as removing the limiter caps without the tool, a sheet metal screw
threaded into the plastic, then yanked outward works, but I would go through the carb first, as adjusting out a problem/clog is a bad idea.