Trying to avoid the cost of replacing the computer. The engine is on a Great Dane Chariot Zero Turn. When you engage the PTO or try to drive the mower forward or backward at high speed with the PTO off it bogs the engine. Starts running like an old hit and miss engine, and any load on the engine will kill it. Fuel rail pressure never falls below 39 psi, using spark testers, it never loses spark. O2 sensor tests at 1.0 volt, TPS test good in all positions, The speed sensor at the flywheel test good, I cleaned the fly wheel and set the gap on the sensor, Tried loosening the fuel cap, Has new plugs, new oil, tested injectors, and coils. Actually I've tested every sensor on it using the service manual. If I remove the computer for two days, then put it back in the mower will run great for about an hour, then starts bogging down again, oh, and when it starts bogging it blows black smoke. Always easy to start but you never know if it's going to run well or like crap when you start it