I used to have the same problem. Make sure your power lines and your audio sends are on different sides of the truck. I have my power on the passenger side and my RCA on the driver side. Ground the amp as close to it as you can. The longer your ground wire is, the more interferance it can pick up. If this does not work, Monster makes RCA cords that have a third wire so you even ground you RCAs independently. Let me know if it works.