Idling really high

hi.  i've got a 1993 b2200 p/u.  it runs pretty good, but one problem i'm constantly having is the idle speed.  i don't have a tach so i'm not exactly sure what its idling at but at it's worst it sounds like i have the gas pressed down about 3/4 of the way, when i'm just sitting at a light in neutral, either w/ clutch in or just out of gear, same thing happens.  then as i let off the clutch to go, it quiets down and sounds perfect, but as soon as i put it back in neutral at any point, it idles really high again.  i'm not really a car person, but i'm willing to learn anything so you might have to put some stuff in layman's terms.  thanks

Just had the same problem with my '86 B2000...  after playing arownd with the carb and lubricating the linkages it would drop back to a normal idle (for awhile).  I had the carb replaced on my truck and the mechanics didn't put the vaccum hoses back onto the correct spots... that seems to have done the job.