AM Radio Static Question...
 

My CDR 210 has increased static on am stations under certain conditions:
1. No am static when stopped at a light, even if I rev up the engine.
2. Static increases as the car speeds up, and doesn't decrease if I push in the clutch
3. I wired the speed activated volume many months ago with no static
4. When I hit the brake pedal I hear a click-like sound in the speaker
5. No issues with FM, only am
6. Yes, I park my cell phone next to the radio; not an issue, tested with phone off

So, is this a ground problem ? or possibly the speed activated volume control ?

Any help will be appreciated. :)