autometer air/fuel meter/gauge question.......

ok....so i've always only gotten some sort of a lean led to light up. it's never gone to stoich and pings at full rich when i unplug it (normal i've heard).
when i turn on the key, the last two lean led's light up REAL bright, then after one of the relays clicks off in the relay panel, the lights dim down. then, if the key is left on but car is not running, it shuts off for a second to the tune of the ISV....ie: when it cuts power or whatever for a second, so does the gauge. start the car...when it's real cold, the last two led's will be somewhat bright, almost look like they move when i give it some gas...after it's warmed up, they dim down, almost non existent.
the key on power is from the oil pressure guage right next to it that gets power directly from the ignition switch. i used like a 12ga-14ga wire to the oil pressure gauge and then the air fuel meter is tapped off of that. the ground goes down to a screw that's in the body down by the shifter box. i cleaned away all the paint so it contacted straight metal.
bad ground? weird power source? (pretty sure it's the red/yellow wire from the switch, but i can't remember to be positive. it was a big f*cker though)
btw....i just changed the o2 sensor tonight.....haven't started it yet to see if things have changed, but as of yet, my guess and theories are leaning twards a big negative.