06 ram 1500, starts fine cold, cranks but won't start when warmed up

After replacing the fuel pump in my 2006 ram
1500, 5.7 hemiz it will start right up if it has been
sitting for a few hours or longer. If you shut it off
after running it, it will crank and crank and might
start it might not. If you turn the key on and let it sit
a few seconds, it will start most of the time. If it
cranks, but doesn't start, then you turn the key off,
and try again, it will start right up. The longer you
run it, or the more times you park and shut it off,
the harder it is to start.