Hi, I start my weed eater and it goes to a very low idle, and when I pull the throttle it shuts off, it sounds almost like its getting choked out...but I don't know why, I changed the spark plug, I checked the air filter, I changed the gas...I just can't seem to find what's wrong with it. Any help or advice would be greatly appreciated.

I would inspect carb and see what the difference is between 1/2 choke and no choke. Set the choke, move the throttle and look into carb- doesnt need to be running. Sounds like something is still restricting airflow at no choke.

chokes are an obstruction placed over the inlet to increase the vacuum in the carby and cannot be pressed
Primer bulbs are used to suck fuel through the diaphragms to expell all of the air in the system to allow starting
normally press the primer bulb until it is full of fuel
apply the choke and pull until it fires
remove the choke and at full throttle pull until it starts

Terry: According to eHow.com:

"

Put on a pair of safety glasses. Remove the fuel cap from the Weed Eater and set it aside. Fill the fuel tank with unleaded gasoline that has been mixed with quality 2-stroke oil in a 40:1 ratio. Replace the fuel cap.

Move the Weed Eater to a safe place and lay it flat on the ground. Depress the fuel bulb located beneath the carburetor approximately six times to prime the engine. Press it slowly so that fuel has adequate time to traverse the fuel line.

Slide the handlebar-mounted engine "On/Stop" switch to the "On" position. Slide the choke lever beneath the fuel tank to the "Full" position.

Depress the "Throttle Lock" lever located beside the engine "On/Stop" switch. Keeping the lever depressed, squeeze the throttle trigger. Release the throttle lock. This sequence holds the trigger in the depressed position, which aids in starting the Weed Eater.

Roll the Weed Eater so that it is resting on the engine and the trimmer head shield only. This will allow the spinning trimmer head to avoid contact with the ground. Brace the Weed Eater by holding it to the ground with one hand. Using your other hand, pull the starter rope quickly until the engine begins to run. Do not pull the rope more than a dozen times. If it fails to start by then, squeeze the throttle trigger and continue to pull until the engine starts.

Allow the Weed Eater to warm up for about 15 seconds, then slide the choke lever to the "Off" position. Let the trimmer run for another minute without touching the throttle lever. After the Weed Eater has warmed up, squeeze the throttle trigger once to disengage the throttle lock. The trimmer is now operational.

Read more : http://www.ehow.com/how_6720315_start-gas-weed-eater.html"

It should run ok after warming up. After starting it, let it run for a minute or so and then try gradually opening the choke. You might try increasing the throttle setting at the same time. After the motor is hot, if you have to have the throttle setting increased in order to keep it running it means the idle setting needs to be increased, usually by turning a screw to keep the fuel valve from closing so much, or that there is a problem with the fuel flow......like a clogged jet or fuel passage in the carb.

check the compression on your weedeater low compression will cause this

Hello Tony Galvan, I had to replace the fuel lines to keep from sucking air when I pressed on the primer bulb. Also, I took the carburetor apart and found the gasket was good by holding it up to the sunlight, no light came through indicating holes in the gasket. Then I took a magnifying glass and looked at the bottom half of the carburetor and noticed that a soft film of what looks like lint from a dryer had accumulated on a screen mesh type of filter. Once I cleaned the debris away, the weed wacker started every time. I pulled with a full choke and partially wants to start. Then moved the choke to half choke and pressed on the throttle fully and pulled, it started! But you must at least hold the throttle close to full until 10 seconds for the engine to warm up. Then move the choke to idle. Hope this helps.
peterjb1

If it runs with the choke closed then it's not getting enough gas. Check the gas filter on the end of the gas line in the gas tank. Remove the gas cap and using a piece of wire with a hook on the end, reach in the tank and pull the gas line out through the opening. Check the filter on the end of it. You could also have a burst-ed diaphragm in the carburetor. This sucks the gas from the tank to the carb. If that's the case a new weed eater may be in order unless you can find someone with the parts to repair it. Also check the gas lines for leaks or breaks, 2 of them.

Usually the diaphram is wore out. It is a relatively inexpensive part. Does it run better with a little choke? If the answer is yes chances are it's the diaphram. Also sometimes the adjustment screws can move. There are two, one for low speed, and one for high. With the engine warmed up make small movements on the screws (some are marked low, and high) in, and out adjust til the engine runs at its optimum.
Hope this helps!

You may need the carburetor adjusted or rebuilt. The other possible item is "bad gas". If the gas has been sitting around longer than 30 days, it may be time to mix up some fresh fuel mixture.
HTH
Good Day.

A couple of things may work...
Make sure you have the correct Oil / Fuel mixture, if it is incorrect the motor may have problems running.
Also take off the bottom where the cord is wound up, make sure there hasn't been any grass get wound up inside it, this will cause it to stall out on high RPM.