Ok, so my mower is a 2000 model 26 hp EFI 42" MT GHS that has 329 hours on it total and a hi dump kit. For the last few months it has had a sporadic check engine light and finally started to exhibit some symptoms recently. It tries to die randomly while mowing, has difficulty throttling up in all conditions whether just started or while being used. But these problems are sporadic, it will go hours without a problem, but the check engine light will still come on from time to time. I tried to take it in but the shop says that the ecu will not interface with their computer. Its my ECU, but theres no way to know what the problem is otherwise unless the guy tries to troubleshoot it for hours and hours starting with the throttle positioning sensor, 02 sensor, and other sensors. It does have a code 42, but the sensor that code talks about (dont remember) the tech tested with a meter and it was well within parameters. So somethings awry somewhere. They quote me a new ECU for 519.00, I cant find one on any website including ebay. Kohlers part number on it is a 24 584 22-S. Its a Kohler Command unit with a metal case, not plastic. If anyone knows where one is cheaper, new or used, or possibly what the problem might be. Let me know. I have put 1000 dollars in this mower since I got it a year ago. I have only put on 50 hours and it only has 329 hours on it total.