I chased this problem for 3 months, it would start at home every time, but after 200 miles of driving no luck. I finally took the starter out and took it down to be checked. It checked out fine, but I was suspect of the magnetic solenoid on top of the starter. I could not find a OME replacement, so I replaced with a standard 12 volt solenoid. I also cleaned all the grounds while I had the starter out. But everything working now.