I have an 85 Z28 with a carbureted 305. When i bought it the AMV was melted and so was the hose that comes the exhaust manifold to it. I hit up a junk yard and got a new one and threw it on. I got about 2 miles and then goosed the throttle and it sounded like it did when i bought it and smelt funny so i stopped and sure as he** same thing. Pics attached. Any ideas whats going on?

 

Figured it out. Cat was plugged giving the exhaust no where to go causing it to get super hot and melt hoses and valves. So for anyone who might have this problem now or in the future...theres your answer. =)