lately, everytime i attempt to start the car it would turn on but act like its about to die, lights from my boost gauge, oil pressure gauge, and cluster would be on but very dim. everytime i would rev it they would become brighter!? this only happens every once and a while.
what could it be?

-bad ground?
-bad battery?
-dirty battery terminals?
-main relay?
-bad alternator?
-bad starter?

im not home right now so cant really check just seeing what you guys think it is