97 Nissan Altima engine problems

My 97 Altima will idle normal then low than as it is doing that it will putt and jerk then die and then after a while i can drive it for a while (usually by the time I drive home from work it will start acting up on me) then it will do the same thing over and over again i have replaced the spark plugs, spark plug wires, distributor cap, fuel filter , intake manifold gasket and fuel filter again.

The car still runs like crap and stalls on me all the time mostly at red lights and stop signs. There's also black smoke coming out of the tail pipe. I haven't replaced the knock sensor (although it's come up on the machine at advanced auto). Should I replace the knock sensor? What about replacing the distributor itself? I've had this car at 4 different shops and $500 later I'm still having the same problem. This dates back to October of 08. Anything you can do to help is appreciated.

Thanks,

Joe

Have you had the ignition coil checked? Sounds like it may be heating up and causing some problems.

No, I haven't had the ignition coils checked. I'm thinking about replacing the crankshaft position sensor next, then possibly distributor or knock sensor. While reading some of the posts in these forums, these parts seem to fix many of the same problems that I'm having with my Altima. I will try to have the coils checked though. What do you think about the other parts that I mentioned?