Don't worry about the venting. We all get frustrated now and again. I just hope you don't throw tools like I've been known to do. If the vacuum lines seem new, then unless one got torn or pierced, they should be alright. You still need to insure that they are hooked up correctly. If they are old, they probably should be replaced. Exposure to heat shortens the life span of the rubber tubing. I replaced mine on my Stallion with fuel line quality hose rather than the cheaper thin rubber lines. It cost a bit more, but the piece of mind with an older car was worth it. It is difficult to see a small crack often enough and that could be enough to lose pressure. It still could be the valve. If the integrity of the lines are all ok and all are hooked up properly, then the valve is the most likely culprit. As far as you owning a 4-door car at your age, my first car when I was 16 was a 1965 VW Beetle and my second car at age 18 was a 1971 Plymouth Fury III 4-door sedan. It looked like an unmarked police car with a vinyl top. In senior high school, one of my friends drove a brown 1971 Mav 4-door and we were seen in it frequently. We weren't self conscious about it and this was in the early 70's when everybody wanted a Cuda or Camaro or Mustang. Drive what you want and who cares what anybody thinks!