I have to make a trip to walmart today...I will get some in and see what happens...thank you so much for your reply...as a56 yr old single female I know a lot of nothing about lawnmowers...only until now, this lawnmower has performed greatAlso, might want to put a little carburetor cleaner in the fuel tank and let that work thru a bit. Might have some clogged jets. Keep us informed on the progress.
Could be something as simple as the little vent in the gas cap being plugged.Yes, it is speeding up and slowing down the entire time it is running. It is still cutting. I forgot to list that it is a troy built with a honda engine....It didnt do this the last time I used it....as I stated it is 2 years old and it is garage kept. So it isnt out in the weather...I hope this exta info helps you help me!! Thank you so much for your reply!!
Im certainly not a small engine mechanic but I was thinking in the line with Joelk.Another possibility is a vacuum leak. (loose carb, cracked/disconnected hose etc.)
Vaccum leak will usually cause the engine to rev higher, and it may then be "bouncing off of" the govenor resulting in the speeding up and slowing down.