Hello all this is my first post on this site. I have an issue with an early 2000's toro z-master z255 model # 74203 serial # 992178. A few times the machine shut off on me while mowing then would start right back up and operate fine. One morning it started right up, but when i pull the either drive lever in with the park brake released the engine shuts off. This happens every time. Also if i pull either or both drive levers in with engine running and park brake set the engine stays running, which before it would shut off. I have replaced brake switch with known good switch, replaced both drive lever switches with new switches, jumped seat switch, replaced ignition and pto switch with known good switches, checked fuses, and even replaced seat delay module with new module. I pulled most conduit off to visually check wiring, and checked terminal tension of all connectors. Nothing i tried made a change, engine still shuts off everytime levers are pulled in with brake released. Any info or suggestions much appreciated, thanks.