I have a 2000 Ford Focus, running a Sony CDX-F7705X Headunit with a 800W Sony Amp and Two Sony 10" Subs. When ever I have my car in gear at a stop the subs work fine, then untill I accelerate to 60 km/h the subs with stay off, so anywhere between 5 km/h and 60 km/h the subs turn off. Any ideas on what is causing that?