I've been in Colorado for about 2 months and had some trouble starting it on cold mornings, after letting it warm up on the block heater for a couple hours, the batteries are not holding a charge when they get cold, so I've been jump starting it with my school bus and that worked fine for a few weeks until the other day when it started right up and was running fine and I stepped away to unhook the jumper cables and block heater and turn the bus off. When I got back out to the truck it had stalled and now I can't get it to start again, usually once it's started and run for a couple minutes I don't have to jump it again it will just start up. I dove into it a little yesterday, let it sit on the block heater for 5 hours and charged both batteries with the bus. It with crank over and I can hear it having compression but there is a hissing sound and there's no combustion.