Recently, my 1971, 240z has been running funny. I go to start it, choke fully on, and it seems to run fine at a high idle, and when i rev it. If i completely release the choke, the car dies after about 30 seconds. Earlier today, i tried to drive it, and its completely powerless. The car is very sluggish, and i barely made it back into my driveway after only taking it around the block. The exhaust is a very dark grey/black color and smells very rich. I cant seem to find the problem. If you have any idea of what this could be, let me know. Thanks

Assuming you have SU's, pull the air cleaner and see if you are getting too much gas. You can also see if the carbs are functioning properly by watching them while you rev the engine. You can also check the carbs functionality with the engine off. See if the carb pistons are moving like you expect.

Check the timing as well.

Just some ideas to start...

Bill