If what you are trying to say is that there was a buildup of pressure in the crankcase (hence the "air" blowing the oil cap off in your hand), I would first check to make sure the positive crankcase ventilation valve/system is not clogged and otherwise operating as it should.

In any event, I don't see how you have connected the the heater, your car's performance, a strange clicking noise, and positive crankcase pressure together? There is no logical connection. Positive crankcase pressure is a problem though (if, in fact, you have it), so get it checked out.

Greg