Husqvarna 142e will not stay running. Going through the sequence of full/half choke it will start and run at high rpm when choked. Even after warmed up, it will die within a few seconds after dropping the choke and going to an idle. I set the idle adjustment all the way up and that did nothing. I tore the whole unit down and could find nothing obvious with the fuel line. Changed the fuel twice, cleaned the spark plug, blew out the air filter...what am I missing?

Hi,
If it is only running high at full choke - then it is not getting enough fuel.
You've cleaned out the whole thing - so it's not air that's the problem. It's running - so it's not a spark problem - it's a fuel problem.

If you have a fuel filter - change it out or clean it properly. If the fuel line is clear, then you need to adjust the running setting of the carb - there are usually 2 setting knobs -one for idle - one for running / mix.
You need it running richer till you get it going - then trim it back to stop it smoking and get a good rev.

Unless your fuel filter is clogged, it's time to rebuild the carb. Watch some videos on rebuilding carbs. Take off both covers and blow out all passages with a short piece of fuel hose. Then change the tiny screen inside, the diaphragm, the reed valve and their gaskets. Don't bother with the rest of the stuff in the kit. Remove the two adjusting needles marked H and L, one at a time, and blow their holes out with a small piece of fuel line. Screw them in all the way, don't force it, them back them out 1 1/2 turns each. Then watch some videos on tuning the carb.