Ok so basically when I'm riding along and I get to around 40mph my car starts to shimmy/vibrate,now it only shakes when I'm on the accelerator but when I'm letting the car coast it rides along smoothly,I'm wondering what would cause this? Also my car has a rough idle when I'm stopped at the red light but when I put it in park it kinda calms down. I'm wondering if it could be the altenator because I do have a 1000watt sound system with 0 gauge wire hooked up with no capacitor. Sn:my low coolant light comes on then goes out randomly...... Thanks any help or advice would be appreciated