Need help please no one seems to know anything.

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Darren about a day ago Car will crank but won't
turn over
It has ran fine for the past five months since I've
bought it. I was driving it home and it stalled in the
middle of the road, so I put it in park and cranked it
and it turned right back on. A mile down the road
later it did the same thing but it was harder to
start. Once I got it started it ran back the rest of the
way just fine. I have changed all the burnt fuses,
checked the ecu, put a new coil on it and tested all
the sparks which were good and I can here the fuel
pump activating before I turn it on. Son I know it's
not that. I checked the main relay and it's in great
condition. Checked all my fluids and now when I try
to start it it's just cranking and won't turn over. But
before I would go out there and rev it up to 3000
rpms then it would die (while in park). So now it
won't even turn on what should I check or  fix?