I have a 2002 Cavalier LS it has 55,000 miles on it when you release the gas cap the car will die or or if it stays running it blows out black smoke. Has anyone ever heard of this before or has had it happen to them?

Why the hell would you do that?

Quick thought on this....turn the damn car off before you take the gas cap off.

ill agree, theres really no need to open the gas cap while the car is running, however, the problem he's having certainly cannot be normal, im very interested in hearing what someone trying to answer the question would say.....

it is my brother's car, I dunno why he doesn't turn it off first but the car shouldn't be doing that. I think he also said he has to pump the gas a couple of times before he can get it to start.

well pumping the gas would do nothing on a cavalier b4 trying to start it because its MP?? holding the gas pedal then trying to start it would.

the reason for the black smoke is that its being flogged with raw fuel.. so this is a strange problem.. is your SES light on?

It might seem the injectors' seat seals are clogged with fine particles that are preventing them from closing fully, thus allowing fuel to leak past and into the cylinders. Start-up would indeed create a flooded engine and a smokey burn.
Removing the gas tank cap while the car is running could be affecting the pump operation if there is much vacuum in the tank. this might mean there is some problem with the line on the tank that should prevent the vacuum from occurring in the first place.
This is all conjecture of course; but it might provoke some indepth brainstorming...lol