subwoofer bass distortion.

Hello, I had a speaker setup in with two ma audio subs and an amp connected all up to my 1999 toyota tacoma, and it worked great!! No problems whatsoever, then I wanted to upgrade my subs and amp. Now, I have two Planet Audio 12" subs, hooked up to a hifonics 1200.1 amp in the back of my truck. I have it all wired correctly, as they work and the speaker output is great, but not nearly 15 seconds after running them, they started playing weird distorded bass tones on top of the song, almost like the idle of my truck was being played in the way of bass. This will happen when I am driving slow in my truck, AND when the volume is at a certain level. When the truck is not running it will STILL play the song good then cut in and out with the distortion on top of the song. Although, when the truck is running around 65+ MPH and the speakers are up loud, there is NO distortion of bass WHATSOEVER! I have checked all the grounds, have even grounded the deck twice. I have a good fuse, and the deck is perfectly fine. I have some things that may be the issue, but I wanted some opinions and help with it. 1. The RCA wires may need to be upgraded from the old ones? 2. The amps Power and Ground cables are built to be an inch away from each other with the radio input right in the middle. 3. I dont have a sound supressor? If someone could help me out and explain what they mean if they suggest a specific part I need to buy that would be great.

sounds like the rca"s are loose or pinched somewhere. try finding an extra set of RCA's and run them over the seats for temporary and see if anything changes. maybe try wiggling the rac jacks to try to reproduce the distortion while the truck is parked. also make sure the ground is big enough for that amp, probably a 4 gauge, and make sure it is screwed tightly to bare unpainted metal and connected with a ring terminal.

Thanks I will buy some new RCAs today and tell you how it works.

buy some cheap ones just for testing because i wouldnt want you to get some expensive ones and that not be the problem.