1999 Honda Prelude problem with idling seems like it wants to die

1999 Honda Prelude mileage: 128,000. I have had the carburetor overhauled within the last 5,000 miles. I have also put a new distributor cap, new distributor, and a new timing belt put on it within the last 10k or 12k. It is having problems when it is idling acting like it is going to die, but when I do turn it off sometimes it's like it does not want to turn completely off. When driving, it drives like there is water in the gas or something, and there is black smoke coming out the tailpipe. I have had 6 mechanics look at it, 2 of which have put on the computer. They say that it is saying it is a map sensor, which really means it's a vacuum leak. The car cosmetically is in great condition, but with this vacuum leak, it is not running well.