Runs fine and cuts but shuts down if I engage the self propelled

So I was cutting my grass and all was fine then Dudley it died. Thought I got too much grass. Started it back up and everything was fine until I tried to move it forward using the personal pace self propelled. I thought it was odd. Started right back up. I could push it through the yard cutting fine with no issues. As soon as I engaged the self propelled it died. Even on pavement. Any ideas?