Tr39NC

Has anyone had an Exhaust Relay Valve sensor error/light appear? I just hit 100,000 miles and am literally having warning lights appear as I'm leaving the mechanic from a previous unrelated repair. Also, my electrical system seems to have some really screwy tendencies. My passenger side power door lock will lock all doors but unlock none. My fan works on levels 4 & 5 all the time, sometimes 3, but never 1 or 2. The upper cigarette lighter does not work at all but the lower does. My radio reception started fading after 2 years and now I receive one or two stations in a major metro area. Only half the buttons on the stereo illuminate. And that's the abbreviated list. Has anyone had similar issues? If so, how did you solve them without replacing every part?