Engine not running smoothly

ill bet this is an older briggs engine ? as they seem to need a little tlc on there governor speed control spring for it's feedback to the throttle , this makes the engine surge a bit (hunting) till a load is placed on it then it runs smooth , now if it doesn't smooth out under load id suspect a carb fuel flow problem

Yes, that is normal operation for an engine. It needs to run at higher idle when cold and the computer does that through the temp sender. Make sure it's not excessive due to any vacuum leaks. This and the AC power loss would be exaggerated if the engine is not running correctly.

The "L" drive was a total pain. It threw exhaust boots on a regular basis. To get it to adjust for idle, you need to put it in the water and run it up to 1500 rpm in gear and get it to smooth out using the idle mixture adjustments. It would almost always be to lean when it ran right, so for idle you would need to run the "jackrabbit" starts until you have adjusted it to do that smoothy. Then your done. If it will not then do all those thing smoothly (idle, run, jackrabbit start) you will need to take the emulsion tubs out of the carbs and clean them.

When they are set properly, you can shine your timing light down the throat of each carb and the spray pattern inside the carb should be identical.

You most likely have a partially clogged carb (main jet) and it isn't allowing enough fuel for the engine to run smoothly. This is fairly common. The carb needs to come off, get disassembled, and cleaned paying close attention to the small opening in the main jet.

Make sure all the springs that go to the carb and govenor are in place. some of them are just used to keep the linkage tight so there isn't any play. Another possibility is that the mixture on the carb is not set right. If you have an adjustment for the mixture, you can try to adjust it. With the engine running and warmed up. Turn the main jet adjustment screw (usually located at the bottom of the bowl) in till the engine RPM's start to drop. Then back it out til the engine runs smooth again. I would back it out another 1/4 turn and try it there. They tend to run better if they are set a little on the rich side.

Another possibility is bad gas.

Doesn't sound like you've considered spark. Sounds like you're losing spark somehow. You seem to know your way around a truck, so I don't have to explain every little thing. Just check all the ignition stuff, go through the distributor and coil and plugs and wires. If it's gettin fuel, its either a spark issue or air/vaccum issue. Hope this helps.

Sounds to me as tho it might need a carburetor adjustment, providing there is an adjustment screw on the carb. Sounds like the engine is running a bit lean. Did this problem occur right after the carb cleaning, or was it there in advance? Is there a fuel filter that might be clogged?

hi on the top of the carb should be a little screw if you undo that and clean it out it might be blocked with dust and grit from being new thanks brian

See if adding oil solves it.

If the idle is not smooth then it could be the Idle Control Solenoid Valve. It must need cleaning.

If it is an old car with carbs, you may want to check the idle. Might be low. You can adjust it on the carb. Or it could be on the air fuel mixture.

It may also be the spark plugs. Check the high tension wires that goes to the spark plug from the distributor if they are loose. You can check if they are working fine if you try to pull out the hi tensions wire plug (the end that attaches to the spark plug on the engine itself) one at a time while the engine is running. If you pull out a plug while here will be no changes in the way the engine is running vs the other plugs, you may have a faulty cable there or a faulty spark plug.

2000 kia will start but it run when u give it gas it goes deadto start u have to hold gas down to floor