[tubman]

Make sure your starter is in good shape. The brushes and bushings wear, and you can even lose an armature circuit or two and the starter will still function. The problem is, they will draw more "juice" than they should that will act as a parasitic draw on the ignition. I had this problem years ago; the car started all of the time, but seemed to struggle. A tune-up helped a bit, but didn't solve the problem.

A properly rebuilt starter did.