John Deere L120 Starts/Runs UNTIL....

[mechanizm]

OK, i have a John Deere L120 lawn tractor with a 20hp briggs v-twin. the float stuck closed so i fixed that and put it back together. started it up and it runs fine UNTIL i engage the cutter then it starts running only at idle speed really rough. i disengage the blades and i can't get the engine to run properly again. this happened to me a few days ago so it sat. today i went out and it started right up UNTIL i engaged the blades SAME THING!.. so i ruled out any carb issues and i'm leaning toward the safety mechanism that won't allow me to get off the tractor with the blades engaged. just to be clear: even after i disengage the blades the crazy bad, slow popping sputtering idle persists. it only went away after i let it sit but came back after i turned engaged the blade clutch. HELP!

 

[BlazNT]

I have to ask. Is this a new tread or are you asking the same question in a lot of different forums? Looks like you are double, triple, quadruple posting.