1981 sl380 will not come off choke

[greg_smith]

Got my merc out of storage last week and i noticed the throttle was sticking open used carb cleaner all was fine for a few days now i have a problem that will not go

As usual when first started automatic choke comes on for a few seconds then goes back to idle speed
Now when started it revs at 1500rpm and will not close down not even when warm

Is there a relay or switch that governs this, i have checked the throttle and all is fine with the linkage

Can anyone help please