Toro Power Washer Briggs and Stratton

I got this power washer for 40 dollars. It never ran consistently and the previous owner told me it needed a new pump. So I re[placed the pump and it would still stall sometimes, so I replaced the gas cap to eliminate a possible vacuum. It still had problems, so I replaced the carburetor, the spark plug, the fuel line, and the air filter. At this point it would only idle and as soon as you pull the trigger it stalls. Then I removed all the corrosion off the fly wheel magnet for the magneto and now it will usually start on the first pull but as soon as you pull the trigger for the gun, it stalls. Keep in mind I replaced the pressure washer pump! it doesn't make any sense. Any help would be greatly appreciated. Thanks!