My 2010 Camry with 223k mi. is now kind of sluggish when turning over the ignition. As I attempt  to crank my car all the lights gets very dim as if its using the last bit of power to crank. In doing this it also doesn't crank immediately. It kind of stalls for a few seconds attempting to crank and then it cranks right up. All this is normally done when my car has sat over night and or sat for a long period of time and sometimes I between going different places throughout the day.  I went to Walmart to check my battery and they said it was good. Also I changed the alternator maybe like 3 years ago. Not because it wasn't working properly but because the body of the alternator where the bolts go to fasten the alternator in place broke somehow. So the alternator was was loose while the broken part was still fastened. So it's not an old alternator. Help!! What could be the problem?