My car sounds like it is knocking sometimes. It does it right after i get out of school. I think it is only when it is cold. This car pulled up beside me and i could like here the echo off his car and it sounds like it is knocking. You can barely here it though. Car runs strong. Dont fell like it is loosing any power, actually it feels like it is getting stronger everyday. After i drove the car for a while and went home, i tryed listening for the sound and couldnt here it. I poped the hood and the only thing that is making any unknown noses is the idler pulley but i think it going out. What could my prob be. My car is a 94 Gt with alot of miles.(149,000). I was linking about running some seafoam through it. would this cause any problems. thanx for the help