Help with carb idle and adjustments

84 LX fully loaded, 2.3 4cyl non-turbo, auto trans.  Appears to run rich.  Idle is 2500 rpm at start up.  Upon warming up begins to surge fast, then slow, sometimes dropping below 1000 and dying.  After warm up, will barely idle.  Will not idle below 1000, just dies.  Surges with auto trans engaged or dies. Does better after running for an hour or so.  Advice?  

I'm assuming you have a Holley/Weber 2 barrel carb. If so, they have a common problem with a idle air bleed passage getting clogged with carbon. It causes a problem like you describe. The passage is a little hole in the top of the carb next to the primary venturi. You could try squirting some carb cleaner in the hole, letting it soak and repeat. There is a trick you can try with the air cleaner off where you hold the the choke plate partially closed and the throttle open so the engine runs around 3000 rpm and keep sealing and opening the air bleed hole with your finger. Sometimes that will clear the obstruction. Of course your problem could also be caused by a vacuum leak. Check all the vacuum hoses and fittings. Pay particular attention to the gasket between the carb and intake manifold.  

The tag on the carburetor says Motorcraft.  There is an inkstamp on the outside of the float bowl that reads 2151.  It is a 2bbl.   There is a butt load of vacuum hoses on this model.  I did check for vacuum leakage and found none. There is a vacuum line that runs from a bank of solenoids under the radiator overflow tank to a vacuum valve coming off the smog pump.  There are two valves close together.  One dumps the smog pump output toward the ground or sends it to the catalytic converter.
There doesn't seem to be any vaccum draw in it which makes me suspicion a control solenoid as the vacuum going to the solenoid controls appears fine.  Of course, the spark advance is tied into all this mess.  Uuuuugh.  Life the year before computers.  

I'm wondering now because the vacuum valve just aft of the smog pump is exhausting its air to the ground (it sounds like a small engine puttering away) if the valve diaphragm is faulty and creating a vacuum leak there, although there didn't seem to be vacuum draw on the line going to that. (I pulled the line and stuck my thumb on it and it didn't seem to make a difference).  I will start by replacing that (provided I can find one) and go from there.  I will also check under the dash for vacuum leaks.  

Sorry, it is a 1bbl.   The carb tag begins with an "A"   It is OEM Motorcraft.  

Looks like I'm going to have to test every vacuum line, every solenoid, and every sensor to locate the problem. What a pain.  

I did some research in the 1984 shop manual. The normal carb for a 2.3L in 84 was a Motorcraft YFA which is a 1 barrel. The Motorcraft 2150 is a 2 barrel. I would recommend eliminating each vacuum line one at a time by disconnecting and plugging the fitting while the engine is idling. One thing you might look for is a temperature sensor that screws into the head or intake manifold water passage. It has a plug on it with 3 vacuum lines. This device switches between manifild vacuum and port vacuum to the distributor to increase the idle speed if the engine starts to overheat. I had one of these go bad on my 84 GT many years ago. Basically gave me a vacuum leak when the engine warmed up but not when the engine was cold. I don't know if the 4 banger has the same gizmo but it is worth looking for. You can just eliminate it with a vacuum line from the port vacuum on the carb to the vac advance on the distributor.  

This sounds like the problem.   I will definitely check it out.  I think several things are messed up.   Cold-Fast Idle speed is set way too high (3500rpm) and warm idle set way low. under 1000 rpm.
As I let it warm up, idle speed drops off to zilch and the car dies.  I restart it, and it idles roughly (as in rough idle) at 850-1100 rpm. I can keep it going with mild pressure on the accelerator pedal, then it surges up and down. After warm up, it idles but surges up and down.  

It is a Motorcraft 1bbl carburator as the A on the tag indicates.  But there is a stamp of 2151 on the carburator.  I know it's not a 2150, but I've read that it is in the family.  I think they used about three different carbs on this model.  The LX 4cyl non-turbo coupe is different from the GT and the turbo 4.

It runs great down the highway at speed and cruise works fine, too.  The trouble is with warm up and idle.  Thanks for the help.  I will pursue your advice and report on the difference.