How to change a fuel filter

indicates fuel leak back and fuel pressure drop
check filter installation for seal not sitting properly, loose fuel line fitting , pump installed correctly (flow wise ), filter installed correctly (flow wise)
air getting in to fuel lines
the thing you are looking for is indicated by the initial hard start but when started runs ok ( good fuel to the engine eventually) and then by the fact that if the engine is allowed to sit for a long period the problem returns meaning that the fuel pressure is not being held
could even be a problem fuel pressure regulator allowing the fuel to bypass ( no pressure =hard starting) then gets enough pressure to run ok but allows that pressure to drain off over time

its in the tank,access through trunk

Your fuel pump may be bad , i have changed fuel filters just to have the fuel pump go out after word if the fuel filter was really bad and plugged up , its like the pump gets use to pushing really hard and when it dosnt have to push so hard it cant push at all now .

IT sounds to me like the two most likely possibilities are the electric fuel pump... or the fuel filter.. If changing the fuel filter doesn't help, you will probably have to go to a shop and have them check fuel pump pressures. To avoid a misdiagnosis, it might be better to just go to a shop where they can hook their computer up to your vehicle for an analysis... Though some shops might change the fuel pump for you simply at your request, changing the fuel pump is too big of a deal to just change to see if it helps... Good luck..

You sure filter is facing flow correctly?:I'd check that first,some cars/trucks have in-line filters.

did you pre prime the fuel filter diesel engines dont like air pockets and the air pockets wont go away on there own did you use oem filter some filters are not built the same

fuel pump

The mechanic should check on the fuel filters , the spray nuzzle and the fuel lines . The fuel filters "the primary and the secondary filters".If these filters are dirty fuel are hard to enter because the dirt keeps on blocking the fuel to pass or go to the engine . The spray nuzzle if it is also dirty then the fuel also is hard to spray or to pass for engine compression. The fuel lines if the fuel lines are worn out or have leak then it should e replaced. These spare parts if they are been worn out or dirty they should be clean or some times be replaced . for good so that fuel will not spill too much on the car.For these problems can cause fuel leaks or engine problems it will result to engine lubrication.

Pull the filters and ck for plastic or o-ring in wrong place. Something is up in the filter. 

The tanks have to be removed in order to change the fuel float sensors.

The hard to start issue could be related to a fuel filter that is full of sediment. The fuel filter could be in the engine compartment before the intake to the engine, but it is more likely an inline filter after the fuel pump on the frame rail. Change the filter and see if that help.