I've got a 96' RS 3.8L v6 with 260,000 miles. I know she's probably on her last leg but i love this car and really want to figure out this problem. when the engine is cold she starts up just fine and drives great. However once I've driven about 10 miles on my way to work it suddenly starts misfiring badly as if more than one cylinder at a time. I've got 2 codes that have showed up about a month ago, one refers to a EVAC purge problem and the other is a "evaporative emission control system malfunction".

 

i think the system is the same for 93 to 97 but not sure so yours may be different. could be a failing or missing gas cap. if not the gas cap test the purge solonoid valve and the pressure control valve. go here and read.
https://camaroforums.com/forum/lt1-lt4-tech-9/testing-evap-system-51219/