When im in traffic, foot on break pedal and air is going(not ac, just the fan) usually on 2 or 3, it sucks a lot of power from the engine and my rpms drop down. Battery is somewhat new and alternator is brand new. Is there any way to change that? I think I had this same problem with my ST back in the day.

Put the a/c on so your rpms drop for a good reason...

Your ac compressor clutch could be stuck

Questionable grounds?

It's not a huge drop, just a little, same thing at night when headlights are on, foot on break, or when I turn on my fog lights, which are 100 volts, so that's understable.

Have you had both the new battery and alternator tested? There could be a slight defect in either one, otherwise I’d agree that it’s likely a ground issue.

Thanks guys.

My idle is fine with the blower on, but does dip somewhat when the amp is running and I hold the brake. It does have a new alt and battery, to add to the discussion like Dan said, so I suspect grounds for myself as well.