My 73 is basically stock, except for under the hood.

Question; At night when I turn on my lights they all look dim.

When I increase the idle speed or start driving they all brighten up. Then

when I stop at a stop sign or light they all go dim again??

Can anyone help?

May depend on whats under the hood...you say it's not stock....

If you have added more power using items then your alternator may not supplying enough juice at idle...also your idle may be too low. sorry can't tell you more without more background ...you can email me if you like..I'm in the members list.