Scag 52" V Ride, 2017 model with the Kohler EFI. Yesterday when I was mowing, the mower chugged hard, when mowing thin grass. I had no issues getting it to the trailer. Belts tight, oil is filled appropriately, etc. I then started the mower while on concrete, full idle, no problem. Engage PTO, mower kills it's self as it doesn't have enough power. Any ideas on what it is?