I own a 86 camaro and it's been running great but yesterday I took it for probably the longest trip since I've owned it and when I got it home and turned off the key, the motor kind of sputtered for a few seconds and I don't know why. Any help?

 

This effect is called dieseling, the combustion chamber was hot enough to ignite the air/fuel mixture without a spark. My 87 when it had the carb on it would do the same thing. This can damage an engine potentially by detonation. How hot was the engine? Might want to check your air dam, coolant, and burp the cooling system.