86 Camaro will not run right when hot 20 mins.

I bought this Camaro and believe it sat for some time. Live in Nevada and had to get it smog checked and it failed. The mechnic played with the carbrator and it passed. I drove it since then and longer then 20 minutes. Then it started to die at stop lights. Hard to get started again but would. Then it would just die while driving. If it would start after that it would cough and belch. Black smoke would come out the exhaust and it would also backfire sometimes. Let it cool over night and I could drive it for about 20 minutes and then it would do it all again. I run it in my garage and after 20 to 25 minutes it does it there too. I get the choke light on when it starts to quit. I have wired it open and let it close but doesn't matter on the problem. The "check engine" light comes on at this time also. Don't know where to go from here. I haven't changed anything cause I don't want to throw parts at it by guessing. A mechanic said it could also be the points module on the distributor. It's not points but a module. Says it could be bad causeing the timing to go off? Any suggestions?

I bought this Camaro and believe it sat for some time. Live in Nevada and had to get it smog checked and it failed. The mechnic played with the carbrator and it passed. I drove it since then and longer then 20 minutes. Then it started to die at stop lights. Hard to get started again but would. Then it would just die while driving. If it would start after that it would cough and belch. Black smoke would come out the exhaust and it would also backfire sometimes. Let it cool over night and I could drive it for about 20 minutes and then it would do it all again. I run it in my garage and after 20 to 25 minutes it does it there too. I get the choke light on when it starts to quit. I have wired it open and let it close but doesn't matter on the problem. The "check engine" light comes on at this time also. Don't know where to go from here. I haven't changed anything cause I don't want to throw parts at it by guessing. A mechanic said it could also be the points module on the distributor. It's not points but a module. Says it could be bad causeing the timing to go off? Any suggestions?
I rebuilt the carborater and it still has the exact same problem. Just quits after 20 mins. of running. Barely runs when restarted. Once I get it started, to keep it running must give it high RPM's. How about any guesses? Help.

Figured out the problem without to much money spent. The ignition timing module under the distributer cap was getting hot cutting out and killing the engine. Change it and drove it to the store. Hope this helps the next guy.

I never would have remotely guessed what the problem with it was. Glad that you got it fixed though, sorry that we weren't any help to you on it...