I have a briggs 16 hp twin I/c model 422707 type 121401 code 9404165b. Engine starts good. But while running about 1/john2 to 3/4 throttle it revs and goes back to idle . Its searching up and down. Anybody got an answer thanks john

Hi,
That model has a fuel pump built into the body of the carb. Two versions existed; held together with 3 or 4 screws. I would suggest starting there as the engine is 15 years old.
Thanks for posting your numbers from the start!
Peace,
Clarke