My mower starts up well, but keeps dying as I mow into thick grass (but not all that thick). Seems power is also not as strong as it was last season. Air filter is clear. Any guidance appreciated.

New gas and fuel filter would be a start. When it starts to lack in power does it smoke and what color is the smoke? Also It would be nice to know what you are using as a lawn mower. Make and model No engine No# would be helpful.

At this point I leaning on a carb adjustment and lacking in fuel or time for new plug(s)

Pull plugs fuel filter ans it this NEW gas form this cutting season?