Took my mower to the dealer to get the drive oil changed. Was recommended to change it at 100 hours and then every 400 hours. After I got the mower back I noticed it was harder to start than it usually was and when I did get it started it puffed some smoke and ran a lot faster at just idle than normal. Have owned the mower for 2 1/2 years so have learned its tendencies and such. When I put the throttle full it sounded much loader and faster and much higher rpms and when I engaged the blades and started mowing it sounded like the motor was "surging". Sounds like it is "bumping" up to the governor and back off . It has a rrR rrR rrR sound but only when the blades are engaged not when they are not. I used to able to mow my yard 2 times give or take every tank but the last 3 times I mowed there is only about 1" of gas left in tank. Went to the dealer and complained about it and they pulled the report and it said the rpms was at 32?? rpms and was supposed to be at 36?? rpms so they set them up to what the factory specs were recommended. Told them about the hard starting and smoke so they told me to bring it back. I did and told the guy at the counter that it used to run and start fantastic and to put it back the way it was and they said they could. Got the mower back and when I started it, it was better but not the same and every now and then it will still puff a little smoke (not as much) but a little and not every time. Called and was connected to the mechanic and told him all of this and he said the rpms was set back to 34?? and I asked him why he didn't set it back to where it was as I was told they would. He said he was never told that. I told him I bring my mower in to replace the hydro oil and they mess with it and screw it up and they sent me a bill for them to try and fix their screw up. It still "sounds" like it is surging, not as prominent as before but it is still there. The mechanic said if I wanted to bring it back and talk directly to him that he can put the meter on it and set it to the 32?? rpms. My question is will it hurt the 691v Kawasaki motor for it to run that way or just run it. It used more gas than normal last mowing but not as much as it did when I first got it back. Looking for insight about what I should do or not do. Thanks.