About 8 months ago I started to notice a drop in performance in my 05 Roush. I use my car as a daily driver and at the time had about 103,000 miles. The first sign was coding on post O2 sensors. So I changed them all, with the problem subsiding for a short period of time and resurfacing again. Then without warning my gauges started doing some weird things. For example, the temperature gauge would signal a low temperature reading followed by my tach being stuck at 2000 RPM at idle. The engine was idling properly but the tach was out of sync and starting out at 2000 RPM.
Finally, the defining moment; Cam sensor fault. So I started doing some research and found out that a diode in the alternator (when failing) allows for ripple currents (electronic garbage to migrate throughout the system and cause a cam sensor fault. It is almost unheard of that the cam or cam sensor is at fault. So I changed out the alternator,re-flashed my car, assuming that there would be remnant garbage in the system memory.
Immediately it felt like I had 50 more HP and all of my issues are a distant memory, power, performance and fuel economy are way up. I am lov'in my car again.
Who woulda thunk it...