'99 briggs 16 Vanguard - fouled plug and no power

[Jerry In Maine]

Thought I had my engine issues fixed but not that I'm driving it a bit it seems not...

Overhauled carb because it was full of goo. Don't know how it ran before that because I just bought it and the dirty carb kept it from running.

No power under load. Coughs and backfires under load. No stable idle under 1200 RPM. After running a few minutes the front plug comes out loaded with black soot. Rear plug is clean and insulator is brown/tan).

Engine doesn't smoke enough to indicate a problem.

I'm thinking the issue is a bad valve. Any ideas?

[mike d]

Hi Jerry. You might have more junk in the carb. I paid to have mine cleaned in a sonic cleaner. It's been fine so far. Try that if there's a local small engine shop. Good luck. Mike d0