I have a Heil model number NDG1050DD01 gas furnace. It is starting to have an intermitten problem of not staying lit. The pilot will light, and a second or two later the flame kicks off. So far I've been able to eventually get it to come on and stay on if I keep turning the thermostat off, then back on to heat and give it 8-10 tries. Any ideas what this could be?

I'm fairly handy with things but have NO experience with heaters. Is this something I could possibly take care of myself? I'm a truck driver and am not always home, so I need to get this taken care of so I have reliable heat when I'm gone.

Clean the flame sensor.