Got Shell 93 Octane and now barely idles 1973 Dart 340

Ok. Not my preferred method, but I would rather not change the manifold. Do you think it's water in the gas? The exhaust is sputtering and I have to enrich the mixture screws close to 3 turns just to keep it idling. Before this problem started they were out 1.5 turns

Thanks,
Eric

You don't have to change the manifold. You can use the plate I linked to.