Hello. My Cadillacs gas mileage has decreased from 12.5 to about 10, idles rough at times (when in drive at a stop light for a period of time), cuts out at takeoff and at around 20 to 25 mph, and it has lost power. The vacuum advance is good, but when I take the line off of the advance, and suck in from the tri-ported thermal vacuum switch, I can breathe right through it. So, I bought a new one, and I can breathe through it too. The only thing is, when I breathe through the distributer port (marked "D"), and I plug the bottom port on the one in the car, it stops. On the new one, when I breath through the "D" port, and I plug the top port, it stops. The one in the car is new as well, and only has a couple thousand miles on it. The one I bought is made by a different company, but is basically identical, with the connection numbers on the same ports as the one in the car, so it is supposed to be connected the same way. Do you think the one in the car is shot, or do you think that there is another problem? I am pretty sure that the fuel pressure regulator is shot, but I don't think that it would decrease my gas milage. It also takes quite a few cranks to get it started (cold start sensor is new and good), which is probably caused by the fuel pressure regulator malfunctioning. Anyways, do you think I'm on the right track, or is my MAP sensor screwing up or something? Whatever it is, it seems to be getting worse (can't get better). Thank you.