Help...what should I do

My machanic is telling me rebuilding the carb may or may not fix my problems. My problems are the choke doesn't seem to be working, it's getting terrible fuel mileage(14.6mpg) and if I don't keep it idle up it sometimes knocks off when I come to a stop. The truck has 143000 miles and has had nothing done to my knowledge. Should I rebuild this carb or spend another 100 or so dollars and put a weber 32/36 on it. I'm really at a point that I'm not sure what would be best and need some advice. I have changed plugs, wires, fuel filter, distributor cap and roter button

I'd test the distributor ignitor and pickup as well. I had similar stalling type issues about 6 years ago, and replacing those took care of that.

If your choke is stuck open, that should only affecting your starting and first few minutes of running, and depnds on your climate. If stuck closed, then you would be starting OK and running OK at first, and then it would get bad.

Is your choke wire plugged into the rear of the alternator like it should be? Take a look at the choke butterfly on a cold morning (see if it's closed), then take a second look 15 minutes later, see if it has moved (opened).

Could you elaborate a little on how to test those two things. At far as the choke it appears the butterfly is operating properly but I have no high idle. The main thing is the horrible fuel mileage. I just got this truck, it had been sitting awhile. I did run sea foam though the first two tanks of fuel. Also when I turn the key to the off position it's like the truck continues to run for a couple seconds and knocks around. I'm thinking the timing is off, any ideas?

What truck do you have? If its the b2k or b22 then to test the ignition module you take it out of the dizzy and down to an auto parts store. It sits under the cap and rotor and goes over the dizzy shaft when attached to the pickup coil. It has two wires attached to it. The pickup coil pulls apart from the icm and you test it by running a resistance check across the two terminals. Idk the proper spec for it however. The stock niki carbs have an anti dieseling solenoid that shuts fuel off when the key is turned off, so you can have the mechanic check that out. A lot of people say it's hard to find someone that can PROPERLY overhaul the niki carbs but if there's someone in your city that says they definitely can do it correctly then I would rebuild it. These trucks run really well when all the emission and computer controlled components are functioning properly but there over 20 years old most the time and are on there last leg.

In addition to all the awesome info already given .. I'd double check the timing just to be sure.. hell .. dawgs even run 180 degress off with the firing order mixed up.. if the timing belt hasn't been done you should pop the upper cover and see if its worn, loose or stretched too.. atleast these checks don't cost you a dime but time