GregR,
Ok have you removed the plastic jet under the idle speed screw?
If not I suggest that you take out the screw and remove the plastic jet and give a good clean out.
If you take it back to the shop they will say it is dirty fuel. You can buy an in-line filter for the fuel line from the tank to the carby.
Get the information from parts list and manuals area under questions on lawn mowers. I have uploaded information on the Honda GCV 135 & 160
Also GSV190 motors.
