khamblin

so i have been trying to figure my truck out over the past while. I got most of the stuff worked out but now there's one more and it should be good... i hope. But when i start the truck all is good. but after a minute of running, or if i start driving the check engine light comes on. and if it comes on while i'm driving i feel it. the truck kinda surges i guess when it comes on then it's fine. plus i have really bad fuel economy. don't know if that's tied in or not. but could this be related to the o2 sensor? still haven't replaced it because i don't have a ton of money floating around, but if it's needed i will replace it.
any thoughts? oh ya it's a 1992 runner with a 22re in it.
thanks