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I'm working on this 1980 truck for my uncle, wished it was mine, he has done a lot of work on it and outside of a new paint job he has nearly reworked the whole truck. This thing has a bad problem with the carb on a part time basis's. more then not it barely will run when you give it gas it stumbles It sometimes runs almost great. He pulled the tank had it cleaned put new fuel pump on it. I rebuilt a carb for it but it had a bad diagram on it that we couldn't find so he bought another donor truck changed carbs it ran good for a while then he gave the other carb away Then it start acting up again. I thought it might be in the ignition so I checked the ignition system. I ohmed out the coil, check the condenser capacitance, points, timing, resistor with my fluke meter I mean the works and it all checks good I replaced one wire I didn't like the looks of going to the points from the coil even though it checked good. Then I started looking at the carb I check the switches on the gas and clutch pedal the transmission because I know this have an effect on it they all checked fine. I believe the solenoids in the carb is working I have adjusted the Idle and idle mix screws when it was running good but sometimes you can just cut it off and recrank it if it was running good before it runs like crap. I have sprayed carb cleaner into ever opening I could find and when it was running good enough I revved it up several times and clasp my hand over its top to try and suck out any junk in the carb, an old trick I learned from someone a long time ago. I removed the wire on the anti-dieseling solenoid but I had to run the Idle screw in so far and I could not get a smooth slow Idle next I unhooked the coasting solenoid and I really couldn't tell hardly any difference if any. nothing seems to work Any one good with these type carbs. I really need some help thanks

Sounds like my psycho carb. Doesn't want to run. Then runs really good. Then runs so fast it is in cruise control. Saving up to buy a weber.

Original stock rebuilt carbs are still available through auto parts stores or on the net. They are usually around the $300 range, whick is more than a Weber conversion.

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OK, I'm over it. Where's the beer?

The three things I have found to cause an erratic idle (from working on many) are: Dirt passing through the idle ports, an erratic or changing float level, a sticking EGR valve that improperly seats each time you open and close the throttle.
Eliminating the EGR valve is easy, just remove and plug the vacuum hose going to it. Do this when it is running good at the time. It sounds like you cleaned out the dirt in the carb already so you probably can eliminate that. Float level- make sure the fuel level is half way across the window in the carb bowl and stays there.
You can't disconnect the anti diesel solenoid and expect it to idle as you have probably found out. Its very job is to kill the truck with the key off.-------Hope you find the problem.

To elaborate a bit on egg's comment. If you remove the fuel bowl cover, make sure you don't lose the float keeper spring on the end of the float shaft. It's easy to drop it, and it's quite small. Without one, the float does all sorts of weird things. Don't ask me how I know.

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"If we did the things we are capable of, we would astound ourselves" - Thomas Edison

Thanks for your tips I had thought about the egr valve it is under the intake the engine was hot when I started searching for the vacuum hose that goes to it so I give up on it after before I got burnt I will look for it next time before it gets hot. As for the fuel level the bowl window always shows a level about a 1/16" below the dot on the center of the round glass window. I figure it should be at the dot but That shouldn't make for this type of behaver. I got a old army friend coming up from Texas I haven't seen in 19 years so I have been busy working around the house and yard so It don't look like a total redneck lives here but I will get back at this as soon as possible. thanks again and if anyone else can think of anything feel free to add to this I thank you allot.

Ok my friend from Texas was delayed so I went back to my uncles Luv. I unhooked the egr vacuum line cranked it let it warm up it did fine then I took it down the road and noted the timing was a bit high before I got back it started acting up cutting off when I let off the gas cranked right back though usually just popping the clutch brought it back to life. Got it home set the timing rpms at about 850 with vacuum advance pulled and plugged "Golf Ts work great for that" I used a hand vacuum pump to lift the EGR off its seat and it died with about 3" of vacuum on it. I worked it up and down then let it slam close the last time. I readjusted the Idle then took it for a spin I like the timing set where it suppose to be at 6deg BTDC you can shift at lower RPMs without it bucking in revolt. "My Uncle had it set up he said it was the only way he could get it to run at one time" well it ran pretty good till I was nearly home then it wanted to die every time I pushed in on the clutch I rechecked for vacuum leaks but found none, "I also check that the Ignition Vacuum diaphragm would hold vacuum and did not have a hole in it." but it does seem to have improved some. I really want to tare into this carb and clean it good but I'm going to have to buy a kit and the last time we had a hard time finding a kit locally. If you have any other advise please help I"m all ears with many thanks.
Wayne in SC

Well I guess things have changed I went to auto zone today and the kit will be here tomorrow. Though it will be next week before I get around to the rebuild. Ill keep you updated

OK got the carb rebuilt today and the truck is running really good I will keep it a day or two just to make sure but I wanted you all to know how it turned out and to say thanks for the help
wayne in SC