Tail light, brake light and battery dash light illuminate at once

The following dash lights go on on my 1990 Toyota Camry: tail light, brake, and battery all at once. They always go on together. They turn on and off as I drive, but are mainly on. All the lights seem to work (head lights and tail lights, I don't have a centre tail light installed). The breaks seem to work fine. And the battery in not discharging. The yellow lamp failure box in the back seems to be fine. The brake lights, reverse lights work fine. I also sat the car for 3 months shortly after these symptoms started and now I notice a new problem that might be linked to the dash light problem. After the car warms up the lights go on and the car has a stumble when accelerating. I will check the spark plug, but I'm thinking maybe a fuel pump or clogged injectors. However the car drives fine when cold, leading me to believe it is not clogged injectors. It seems electrical to me. Any help?