I need help adjusting the idle and carbs on one of my Husqvarna chainsaws.  Well, originally all I needed help with was the idle, but I started screwing with the thing before I knew what I was doing.  Anyway, the saw has three screw adjustments, each labeled "T", "L" and "H".  Unknowingly, I adjusted the L & H screws before I realized they have nothing to do with the idle (the T screw controls it).  Now, I have gotten the carb out of whack and can't figure out how to get the L & H screws properly adjusted.  Any set rule to for these screws, or do you have to play it by ear?  It basically will start, run pretty high, and then die out.  You can sometimes keep it running with the throttle, but it will bog donw.  Mind you, before I got ahold to it, the saw ran perfect (just idled too high).   Any advice is greatly appreciated!

start with them both out 1 turn. run the saw until it is at operating temp(few minutes).Make these ajustments slow and at a rate of 1/4 turn at a time...............

Adjust the "H"(high RPM) first by turning it either in or out while holding the throttle wide open to get the highest RPM's you can.

Use the idle adjustment at any time to control Idle to a point where the chain doesn't move on its own, yet keeps the saw running well.

The "L" (low RPM) adjust this screw in or out so you don't have a "BOG" if you quickly give it a burst of throttle, it should be adjusted so the off idle is very crisp.

Now revisit the "H"  and adjust again for MAX rpm, back it down just a "C" hair.

The 2 fuel circuits overlap and each has a slight effect on the other, thus the reason for re-checking the high side. keep in mind a temp change will have an effect on the settings. IE tuning it in winter 20 degrees then using the saw in the summer at 90 degrees will require a re-adjustment for optimal running.      

This might help, though not Husqvarna specific:

http://forestapps.com/tips/carb/carb.htm