[roger albert]

Battery or connection wires at base of key switch, or other loose connection first.
Dr. Curve's advice is good on the injectors (I've seen it too) but your dim lights imply an electrical issue first. Get the electrics sorted and fresh plugs in there, and if you still have problems, then look into the injectors and fuel system.

Raw gas will damage your O2 sensor, so don't be surprised if you have upper rpm problems once you do replace the battery.

Right and very probably wrong. Yes, the raw gas is tough on the sensor, but no, it doesn't normally cause a high rpm problem. On the contrary, is causes a low-load/low-rpm/steady-state problem, since at high throttle and rpms, the sensor input is irrelevant anyway.