Starts and runs but than when I try and cut wood it loses it's power

clutch failure

You just do not have a saw that has enough power, the blade is dull or both. Change your blade and push the wood through slower or get a more powerful saw for the hard woods.

carb needs overhaul or high speed jets need ajustn--hav a pro du this cause if u lean it out too much-u can fry the engine--clymer makes a mechanics manual for motorcycles and atv

fuel problem. either the fuel or air filter is plugged or the jet has something in it. or the carb gasket is bad and allowing air in

Hi goincrazy, check that your carb tubes are ok, and your exhaust filter is clean, also clean your fuel filter or get a new one. Hope that helps
Steve

Idle settings is not good maybe some crancase sealing is faulty.

The chain only comes off the bar if, the chain has become lose and de railed, or if the timber you are cutting is very springy and you are trapping it in the cut, our twisting it in the cut, if the saw is not oiling the chain correctly it will stretch and if not addressed will come off, once it has come off the drive links are usually damaged, you should realy start again with a new chain, when running close to a clean peice of wood you should a steady stream of chain oil coming from the end of the guide bar.

Sounds like the wood your cutting through is to hard for your battery powered saw....try one with a cord they work much better, especially for hardwood's.

Tensioner worn or mal-adjusted.
Blade blunt.

Check the muffler screens first. Then the spark plug. If not the case, then adjust the High setting on your carb. Prolly starving for fuel under engine load. If it is still a problem, Pull the carb and clean it.