Compression Test Results

I recently rebuilt the top-half of my stock 1.3, because it overheated, was blowing smoke from the exhaust pipe, and when I pulled the valve cover, I found antifreeze. I flushed the coolant system, new head gasket, new intake and exhaust manifold gaskets, and it ran perfectly for about a week. Last night, I ran to Domino's to get pizza, and it was smoking from under the hood. I found oil everywhere, including a trail behind me. I immediately took it home and parked it. This morning I looked into it and found oil in the intake. I did a compression test. I got (cyl-pressure) 1-148 lbs, 3-110 lbs, 4-75 lbs, 2-45 lbs. I don't know what to make of this. Only thing I can figure is that my rings are shot, and the oil build up is creating too much pressure in the crank case, causing oil to blow from the valve cover into the intake. Before I go tearing this motor down, I'm hoping for another possibility. Minimum compression is 149lbs, standard is 203lbs. Any ideas are most appreciated.