'it idles very high to low and continues to do so until I engage the blade'

And presumably it cuts fine with the blade engaged? I'd keep using it and run Seafoam in the gas until it dissolves the gum and varnish in the carb.

I'm guessing it stalls. I very seldom see gunked up Honda carbs.

No it doesn't stall. I didn't know if I would make things worse be running it. I assume then in time it will corect itself?

It could be running lean at low speed, but when under a load, the main jet takes over and it runs well. Keep using the seafoam.

Did you ever get this problem solved? How?

sounds like the home owner ripped you off with a lawn mower they couldn't fix.