Maybe when you wiped the engine off with a towel, you pulled loose a wire. Water in the engine bay should never cause a problem. I was my engien all the time on every car I've owned and never had a problem. What do you think happens when you're on the freeway and it's pouring rain.... your engine gets steam cleaned!

CHeck ALL of the enigne connections. In particular, check the throttle position sensor, cam or crank positon sensors connections and any wires on the transmission.