Recently, past few weeks, my car has been really difficult to start sometimes. When it doesn't start right, it normally takes about 15 seconds of cranking until the car starts. Normally it is only about 2 seconds when cold and almost instantly when hot.

The strange part of this is, it does not matter if the car is cold of hot. A few examples after being run until hot:
sitting 7 days, 15 second start
sitting 5 minutes (gas fillup), 15 second start
sitting over night, 15 second start
sitting 13 hours, right away
sitting 5 minutes (gas fillup), right away

One the car is started the car runs great, 17.5 mpg, normal amount of power, no strange noises, and is very smooth.

any help would be appreciated.
Thanks,
-Kevin

 

Could be your check valve in the fuel tank is allowing pressure to bleed back into the tank. Requireing the line to be represurized each time you crank it.