1986 Ford Ranger Stumped

The first things noticed were decreased powed and extremely reduced fuel mileage. Once on the freeway also noticed that once in a while it will hesitate. If givin full throttle it bogs down. Also when stopping at a light the truck idles sporatically and most the time will die. Also when stopping I noticed there was an odd smell (not gas or oil, or regular exhaust) Once it dies it usually takes a while to get it to start back up. I thought it might be an issue with the cats but upon checking the forward one I found there isnt even anything left in it. I dont know if maybe the back cat is now clogged or if I am way off on my ideas.