It is 1 degree right now, I started my B2601, and let it idle for about 5-10 minutes (no block heater) then when I began to blade our drive. Within the first 10 feet it began to drop in rpm, so I stopped, increased the throttle a bit and began again, the rpm's just keep revving up and dropping down, even when at a stand still. I was barely able to get it out of the drive and back out of the way. We do use a diesel additive to avoid gelling. Not sure why it is revving and dropping rpms. But I cannot blade my drive with it like this...any help is appreciated.