Starting issues

lcan5150

I have a 2003 Yukon XL that has been experiencing major starting issues. It started out with not starting at all but it was diagnosed as the kill switch system which has been removed and now that the car is starting it has a very slow start. The alternator, starter, and battery have all been replaced, however it still acts like the battery is not getting a full charge. Any one have this problem and or any ideas of what to do next?