Washed engine, now runs rough

I Power washed the motor and used degreaser too. I dried out the distributer cap and the coil with an air hose thinking this was the simple prob. It runs fine at first but once it heats up and I stop at a light, the tack dives down like it's going to die and sputters off like an old junky carburated engine until I get it up to over 40 miles per hour then it runs like a champ again. I'm so confused.... help