1993 Chevrolet Blazer 93 S10 Very Low Miles Previouse Owner Drove About 10

I have a 93 s10 blazer with very low miles. The previouse owner drove about 10 miles a week. I drove it for about a month and did some basic tune- up stuff before taking a road trip. I use the same gas religiously, (at least the same co.) and had no issue until I returned home. I then started having a sulpher smell from my exhaust. This went on for about a month and then I started experiencing a stutter in my acceleration. Now,two weeks and one tanl later, my milage has almost been cut in half! But there is no check engine light. I know it works. What can I do to fix this?
Thank you.
T