The first thing I would fix is the over revving , the governor is not working properly or incorrectly adjusted .
In the image below the throttle cable goes to full rpm when you adjust the throttle lever on the handle then further movement moves the choke into the closed position ,so with choke fully on it should not put any more tension on the governor spring than at full throttle with choke open.
or another way to put it ,with choke fully on, the spring tension on the governor should effectively be the same as at full throttle with choke open; the difference is that the choke plate is now closed, not that the governor is “pulled harder.”
If pulling the lever into choke seems to pull the governor spring noticeably tighter or changes the throttle plate position beyond normal full‑throttle, then the linkage is mis‑routed or in the wrong holes.
You should be able to set full throttle on the carby and adjust the governor so it's not over revving ,then when choke is on it's not changing the governor tension.
Sometimes it's not worth spending a lot of time on cleaning a carby if they are cheap to buy new.
It is very likely but not guaranteed that the stalling is from the idle / transition (intermediate) circuit still effectively lean or partially blocked. Why it points to the intermediate circuit
If an engine will run strongly on full choke but dies as soon as you open the choke and try to go to idle or just off‑idle, that usually means the normal fuel path (pilot + transition ports + main) is not supplying enough fuel, so the engine is depending on the extra fuel from the choke to stay alive.
On the GCV‑series, very small amounts of varnish in the primary jet, emulsion tube, or the small progression/transition ports around the throttle plate can cause “runs on choke, stalls off choke” even when the engine will rev if you force it.
