My roommate has a stock '95 240sx and his waterpump began to leak. He drove it for a couple of weeks (adding water constantly) before I changed it for him on tuesday. He is not the most mechanically inclined and he said that he was driving it on the freeway a few days before when it started running really hot. Now after I replaced the thermostat and waterpump, he says the car is idling rougher. He says the tailpipe smells rich, which it does but does not seem abnormal for just starting it up after a few days. Now he wants to change a bunch of other stuff and and take it to a mechanic. Could the heat have caused a problem that could have led to the rough idle. Thanks for your help.