HELP ASAP! Electrical Problems

Yes.
What car is this in?
Everyone would assume you are talking about an A body.
But I don't see that in your post.
If so, the pegged fuel sendiing unit is typical of a stuck "voltage limiter" on the back of your cluster.
The dimming lights are a puzzle.
Could it be that you were stopped to make a turn and the engine speed was just slow?
This is typical of old Mopars too in that the alternator isn't turning fast enough to put out.
We all have been freaked out by a problem and started noticing something that is there all the time.
We then think it is a new or related "problem".