Engine bucking and exhaust backfiring after turning off ignition and driving car for ten seconds. Continue to make these noises in video for 10-30 seconds (depending on how long it was driven). Car hasn't been run in a year and half and new carburetor was installed. Any ideas what is causing this? 1987 trans am 5.0 liter carbed.

 

So it runs OK, but when you kill the ignition, it continues to run on for 10-30 seconds? If that's what it's doing, that's run-on or "dieseling". If your idle speed is set too high with the new carb you just put on, it will do that. Also, if your ignition timing isn't set correctly, it can contribute to that as well, but high idle speed is usually the more likely cause.