If I am working on a project and I sub out work to an insured sub, can I still be held liable for the work of the sub-consultant?

Yes. A consultant remains liable for the acts of its sub consultants. Depending on your agreement with the client, governing law and nature of the claim it is possible that the client will not have a direct action against the sub consultant. It is good practice to make certain the your sub consultants have coverage equal to or greater than your own. However, the existence of coverage does not provide a shield as respects your liability to third parties. It will however provide a source of recovery in the event that you seek indemnification against the sub-consultant for getting you embroiled in their mistakes.