I just had a new well dug (240') and the water ran fine for a week. Now it has terrible issues with air in the lines - constantly spitting and sputtering and gaps of no water. If you pour a glass of water it is brownish and full of tiny bubbles. Well driller says it's in the water and nothing I can do. This is hugely disappointing and at a considerable cost. Does anyone have a resolution?

The great likelihood is that the water table has fallen to around the level of the pump. That allows the pump to pump air/water mixed. Lowering the pump might be helpful, but I would think your well guy should have an answer.

One more thought. You might try not using water for a couple of days and see if the problem goes away. It will likely come back again, but that would show that the well had time to recover and gave good water again until the level dropped.