rough idle

so was on the way home from work and all of a sudden my truck lost power but was still running. pulled over and looked under the truck and saw the cat was glowing orange. let it cool down and limped it 4 miles back to my work (I work in a diesel shop). used 1/8 of a tank of gas just going those...

I have a 96 s10 with the 2.2L and a 5 speed with 170K miles, my truck is idling rough and my mileage is slowly getting worse. Im averaging between 21 and 23 mpg around town, I used to get closer to 30 mpg. Also sometimes it doesnt want to start on the first try, but fires up on the second...