Car idle is low and creates black smoke at high rpms

[silent]

(a little background on my zx...It's a 1979 fuel-injected 280zx stock. The car sat for 10 years before I was given it. I took it to a mechanic who replaced the gas tank, fuel pump, radiator, spark plugs, wires and clutch (he cleaned the injectors). I paid 4500 bucks for everything... and now my car won't work. Shitty deal!)

I was driving my zx after work. Car was moderately cold and after about 3 minutes of driving the car simply shut off while I was driving. (I was at high rpms while I was driving it. I was screwing around with a friend in a parking lot. Pretty damn stupid thing to do when a car is cold, especially an old car.) I pulled off to the side of the road and tried to start it but it wouldn't give. From what I could hear, the engine wasn't recieving any fuel. It never caught, or choked on any gas at all. (electrically the car is perfect, it turns over just fine.) After the car wouldn't start, I lifted the hood and I heard a hissing noise. It sounded like air was escaping from somewhere.

The next day the damn thing started, but it sounded like $^!#. The rpms were at 250 and the car sounded like it was going to die on me. I revved the engine around 6000 rpms and a ton of black smoke came pouring out the exhaust. - I don't imagine this is a good thing. Also, after this the car wouldn't start again. When I waited 10 minutes, the car started. After I shut the car down it seemed like I'd have to wait 10 minutes before I could restart it.

A friend of mine said it could be a cracked piston or blown headgasket..., my tow truck operator says it sounds like a screwed up timing belt, my dad says it sounds like a fuel pump/injector problem and my mechanic says the hissing sounds like a vacuum problem.

I don't know much of anything about cars and I don't have the money to fix the car right now, but maybe one of you guys has had the same problem and could tell me what's wrong, or at least what you think is wrong.

Any help would be really appreciated. Thanks.

And man, this sucks

[st0878]

Black smoke is caused from a very rich mixture, especially at higher RPMs. Let me guess the car doesn't like to start when it's hot?