My1986 S-10 2.8 barely idols and smells bad, runs ruff until at highway speeds, gets bad milage, some symptoms started after replacing orings on injectors, but they aren't leaking?

no the injectors are not leaking but the top plate where the fuel pressure regulator might be causing it not to work or you have a fuel pressure regulator out causing excess fuell pressure to go through the injectors. this would cause bad mileage and unburned fuel smell and bad idle. going down the free way and or driving it might be better because you are using up a lot of that excess fuel that the regulator is not mettering. they are cheap you should just replace it with new and see if that help. the bad running is the engine is flooding out like it has a choke fully closed