2009 Hyundai Sonata slow cranking/no start

Hello,
I have a real weird problem with my 2009 Hyundai Sonata 2.4 L. For a few
months have had issues with the ignition. When you start the vehicle the
ignition would kick in again and try to restart the car. Today I was sitting idling
and the car just died on me. So I went down to the parts store and bought
the new ignition piece and installed it with no trouble. I thought maybe the
ignition finally went and perhaps this is why the car died. Well it took care of
the first problem of the car trying to re-engage while starting but the car was
acting like it had a dead battery. It was cranking over very slowly. I once
again went down to the local parts shop and purchased a brand new battery.
This started the car one time although it sounded like it was having a hard
time starting. After I shut the car off it had symptoms of dead battery again. I
took both my old battery back to the parts shop and had them check the
batteries and they said both batteries were good. I left with new battery and
re-installed into car and was able to get it running again (with a boost) but it
sounded like it was having a real hard time starting. No weird noises just
sounded like it was starting on a dead battery. I am at a lose for what to try
next. I was thinking about pulling the starter and having it checked but I don't
see how this would have anything to do with the first issue where the car just
shut off while idling. I should mention that everytime I have been able to start
the car with the new battery and a boost the car runs and drives just like
normal. As soon as the car is shut down its almost like it has a dead battery
again and is struggling to start if at all sometimes even with a  boost. Have
checked the charging system and all seems to be in check, with car running I
was getting 14.7-14.9 volts.
Any help or opinions would be greatly appreciated!

Thanks to anyone that can help in advance