Can anyone help? I have a Mountfiled Empress 4hp petrol mower that I
obtained from someone who inherited it and wasn't sure if it was working or
not. I got it home, put some unleaded petrol in the tank, checked the oil
level and cleaned the air filter. After only a few pulls of the pull-cord,
it fired up and the engine seems to run smoothly and steadily. However, it
does seem to lack power and after cutting some grass for a few feet, it
seemed to gradually lose power. This continued even with the blades lifted
off the grass, and no matter how I set the throttle.

Can anyone suggest a logical sequence of things I should check?

TIA for any help!

Al