87 mazda b2000 carb issue

Have a 87 b2000 with 117k original

choke doesnt workl well,have to tap the gas a little to keep it running

once warm it runs fine but somtimes it will idle at 2k and wont go down unless i put the clutch in then it kicks down to 900 or so were i usually have it

any help
hows the carb related to the trans?
will do this every time