Nothing you add to the fuel will help the boost sensor, which is in the air stream, not fuel. It could be the water shorted out the overboost switch and it's triggered now, which means the car takes off OK, but is a dog above ~2500 RPM. It should dry out and return to normal in a couple days if that's the case. Could be a plugged overboost switchover valve too, but washing the engine shouldn't cause that. If the car is a dog off the line, you'll want to adjust the ALDA to get some more power - use the "Search" button and you'll learn all sorts of things on this forum!
