Spark plug wires?

A couple to start with.  Check fuel pressure at your rack after you
turn the key on.  The fuel pump should run and pressurize the rack
before you start the vehicle.  Also, try to get some resistance
measurements on your injectors.  Maybe you've got an injector that's
starting to go faulty.  Resistance measurements should be listed in any
DIYers repair manual.

had a real similar problem with 2000 V8, 79000 miles.

dealer replaced fuel pump, and possibly some fuel line.

fortunately, it was under extended warranty.

Tell me what you think...

'99 Mercury Mountaineer, V-8 5.0L engine, 98K miles.

Lately she's been getting harder and harder to start.  As in not REAL
hard, but she cranks for a good 2 seconds before she catches.  Once
running, no problems.  No recent changes in engine performance or
MPG's.  But, gradually and consistently taking longer to start, in all
conditions.  Battery's real strong, so that's not it.

I've put in new double platinum spark plugs, had the fuel filter changed,
had the local shop perform a fuel-injector cleaning service, replaced the
air filter, cleaned out the throttle body (it had the sticky accelerator
pedal
problem which is now cleared up), put in some fresh Mobil 1 5W-30 and
a new filter.

I even bought her some new tires then told her how pretty she looks...

No change.

Any ideas?

Some people have said this can be caused by the fuel check valve and
or line that's inside the tank deteriorating.  My 92 periodically does
the same thing.  It will do it for a few months and then it goes away.
I had a shop check the fuel pressure, etc and they said the pressure
was OK and could only suggest a new fuel pump based on the possible
check valve issue.  For $500 I decided to wait.