1990 Cadillac Deville won;t start

The car recently broke down on my wife. I would normally be doing any repairs, but this happened an hour and a half from our home, and we couldn't get the car here. Anyway they said it was a shorted wire leading to the distributor, since it would start then die. We finally got the car back, and it seemed to run fine for awhile, but if the car sits for more than a couple of days it is hard to start. Now that it is so cold the engine cranks but still won't start, and I have no fuel pressure at the test port. I also noticed the fuel tank seems to have excessive pressure when I go to get gas in it. The fuel tank, pump, and filter have been replaced within the last 2 years.