The first thing you wnat to look at when you have a carburetion problem is the fuel lines. Make sure they are not cracked or split. They will pull air into the fuel stream and allow it to run lean. On the 029/MS290 you can see the line after you remove the air filter. It is under the carburetor.
The second item to check is generally the fuel filter. If it is slightly plugged it will not idle correctly. the fuel pump in the carburetor works off of an impulse of the lower crankcase. It is not a high pressure system, a partially plugged fuel filter will not allow enough fuel at idle.
The original 029 had H and L adjustment screws as well as the LA screw. The H and L are mixture screws and the LA screw is the throttle plate positioning screw. The LA screw holds the throttle plate open a bit so the correct idle is maintained.
For a saw that has not seen regular maintaince, don't rule out that the saw is running fine and you may have another problem. If you have not grease your sprocket bearing or if you have a broken clutch spring, it will put a load on the engine at low RPM and it will die instead of idling. A quick way to confirm this is to remove your bar and chain (the load) and see how it runs. If it idles fine, there is your problem.
The preliminary carburetor adjustments eon an original 029 is the screws fully seated in snuggly and then out 1 turn. If the saw is equiped with "Limiter Caps" you only have about a 3/4 turn range. The limiter caps are generally the black piece of plastic surounding the adjusting screw.
