1989 Toyota Corolla Flooded Engine?

Recently I went through a large puddle in the middle of the road at night, which I did not notice till the last second. Afterwords car seemed to have had a loss of power and a rumbling noise began occurring from underneath the vehicle, specifically from where the cat is situated. I checked the engine bay and the fluids, and all seem dry, although the loss of power and noise from underneath the vehicle still persist. What could the problem be? Did water get into the cat or another component of the exhaust system? The vehicle does seem to idle fine and start up quick. Also when I have it in neutral and I rev till the rpms get up high the rumbling discontinues till the rpms are brought back down. White smoke is also visible upon cold starts from that area underneath the vehicle.