I would pull the plug and have a close look and see if it's burned the plug, replace it if in any doubt, check the fuel supply line, if you can blow everything out with air (carefully) and really clean everything up and make sure the linkage etc are all clear and not binding or filled with dirt etc.
I would also suggest buying a can of Husky Pre-mix which is not only mixed 94 octane & 50:1 oil but it has a conditioner in it. You'll also know that the gas is good (apparently there has been a few not so great batches of gas hit the market).
Even though there is a spring on the idle screw, these buggers vibrate like hell and after a while it can dial out as a result. The spring can be replaced (get the right one for the job) also check the carb screws etc to make sure everything is still tight, maybe sucking a bit of air in. I only say that because you say once heated up it (15 min run) it goes back to good idle.
I would also suggest buying a can of Husky Pre-mix which is not only mixed 94 octane & 50:1 oil but it has a conditioner in it. You'll also know that the gas is good (apparently there has been a few not so great batches of gas hit the market).
Even though there is a spring on the idle screw, these buggers vibrate like hell and after a while it can dial out as a result. The spring can be replaced (get the right one for the job) also check the carb screws etc to make sure everything is still tight, maybe sucking a bit of air in. I only say that because you say once heated up it (15 min run) it goes back to good idle.
