I own a 2005 Ford Focus w/158,000 miles. It has been a great car and would like to get another couple years if possible out of it. Many times when I go to start the car it sounds like really weak and sometimes almost like a grinding sound. I know my battery is fine and other times it has no issues and cranks right up. I have been having the issue for over a year. The car starts consistently every time, but feel that I am on borrowed time and the car is going to leave me stranded. Could the starter be going out? I have the skills to change it out myself, but could it be something else besides the starter? Should I get it diagnosed by a professional or would you just change out the starter? What are your thoughts? Would you pay $100 more for a Motorcraft part?