You may have sticking or leaking injectors. I have seen it many times. You get a little trash or rust in the fuel rail and a piece of something gets caught in the injector. It may not be enough to cause a misfire code but enough to cause it to run a little rich and rough. The systems on the 94 and 95 models are not as sensative as on the later models. A misfire or O2 code may not appear as quickly.