I've got a stihl 028 av.The chainsaw idles perfect.Just had the carb and new seals done on it.The problem is when you hold it full throttle it revs up and down bad.I thought it was loosing vaccum pressure.Like i said i replaced the seals and it's still doing it.I've got 200 bucks invested and i need help.Please help me.Thanks,Terry

Terry White., August 2009

I take it that the rings are fine and the piston is not loose in the bore to get back presure in the sump. Check that the exhaust out let is not blocked with carbon, even start it without the exhaust, to make sure no back presure. check the air conector to the carb it may have split.

Derek, August 2009