Runs rough when warm, at low RPM's

[bobrocken]

recently my heater bypass hose ruptured while driving, washing the top of the engine, of course. As I was traveling at about 50 mph when it broke, I wasn't aware if it until I slowed. my idiot gauge appeared to be slow in informing me. I slowed for a light, and observed steam rolling out from under the hood. Looked at the gauge, and THEN it started to rise. I immediatly pulled over and repaired the hose and re-filled the radiator.
Ever since, I have had a problem.
When the engine is cold, runs great. When accelerating, once the RPMs get over approx 1300, runs great. but, once warm, when trying to deadfoot, and when trying to slowly accelerate, it runs very rough. can't get out of it's own way. not enough HP to accelerate. but when I put the pedal down hard, it eventually takes off great.

HELP