Remove the muffler and have a look at the piston and rings. If they are scored or sloppy, the engine is worn out. With the starter off, check for any side play in the bearings by wiggling the flywheel. The coil could be bad but that is an expensive part to replace and discover it is not the problem.

Thanks canguy. Last year I rebuilt that saw. New piston & rings, rebuilt the carb, new gas line and new impulse line. Since then I always use stihl oil in my gas mixture so not to score the pixton again. I have the muffler off right now and the piston etc looks good. That saw ran as good as my new 270 and then all of a sudden started to give a problem.That new impulse line has a loose fit unto the carb and when the saw gets hot I'm wondering if that isn't my problem, that's a $8.00 item but a real pain to change. I'm trying to come up which a plan to make the hose tight to see if that was the problem, haven't figured that out yet. I'm wondering if a bad coil could cause my problem. I took a chance and bought a new one last night off e-bay, $27.00 plus $5.00 S&H, suppose to be new, I'll find out. That is a good price if everything is on the up and up but you never know with e-bay. If it's good that's better then $80.00 retail.

A bad coil would not be any different when cold or warm. Sounds like a problem with your impulse line or possibly just an out of tune carb.