340 not running anymore...Help Please?

Holleys don't "sit" well. I advise to rebuild them at least every two years. The needles and seats are easy to get crud in and stick and I think that's what's happening. Change the fuel filter (install a steel body stock type...no clear or plastic ones). Pick up the nylon needle and seat gaskets for both bowls. Pull the needles and seats and blow them out with carb clean. Then re-install and set the floats. I think it's flooding out.