pilot keeps going out

So many possibilities, as Captainco said, could be a draft/combustion air issue, could be gas pressure issue. Is the pilot clean and adjusted to a proper flame? Have you watched the boiler fire under its normal operating conditions (door to room closed, cover on front of boiler, etc)? any cloths dryers or stove exhaust fans or the like that could cause a lazy start that is blowing out the pilot on ignition? Has the venting been inspected as far as is possible to insure that it is the right size, and within specs on any horizontal branches according the IMC?

In my experience an intermittent pilot failure is usually caused by something wrong when the boiler fires. If it can't light off properly and rolls out, or it creates too much draft initially (rare) the pilot can go out. You just have to start eliminating possibilities one at a time. Start with checking draft under normal operating conditions as stated above, make sure there are not fans or anything running, make sure it is in spec there. Then do it again with all bathroom fans, clothes dryers, stove hoods etc, running and check it again. Still good? move on to the gas pressure. Make sure your mainfold pressure matches the rating plate, check your orifice size and make sure it is correct, check your inlet pressure (static and running), watch the pressure for awhile while it is firing to make sure the gas company's regulator is not wandering. So on and so on, and eventually you find the problem.