I've got an Apex 60 with about 90 hours on it. It just started this deal where it does about 20 yards or so after starting the mowing deck. It's been serviced and I just rebuilt the carb today with no improvement in performance. I can make the same loops around the yard with the deck off, thinking it may be the camber of the hillside, but it runs just fine. As soon as I engage the deck, I can go about 25 yards and it sputters and dies. It starts back up and runs fine again until I re-engage the deck. I'm at wits end with this thing.