Cranks but does not start (2001 Explorer Sport)
 

2001 Explorer Sport 4.0 SOHC automatic 190k miles

Vehicle began having issues accelerating due to misfire(s). Replaced all plugs/wires about two weeks ago and the vehicle ran very well.

About a week ago the vehicle started doing two odd things:

1. When placed in Park the vehicle would suffer a drop in rpm and either immediately die or struggle for a few seconds before returning to normal.

2. Some days it just won't start. It cranks strong, I've done the spark test on all plugs, but the engine does not start. When it does start, I have to be ready to give it some gas for about five seconds or else it will struggle for a few seconds then die.

Until today, it was simply a matter of waiting for as little as ten minutes to try again and then it would start, albeit with me having to hit the gas right away. No problems at all driving it, and idling in Drive (at a red light for example) was no problem at all unlike placing it in Park.

I can hear the fuel filter engage when the key is turned forward, and the smell of fuel is pervasive when performing the spark test.

I do not know what else to try next.

Just a thought, but it sounds like the fuel pressure damper/regulator is bad and allowing fuel to enter the intake thru the vacuum line. This would in-turn flood the engine out unless you stepped on the gas to allow more air into the engine to compensate for the excess fuel. I would check for fuel in the vacuum line that goes to the fuel pressure damper/regulator. If the diaphram is breached, then it needs replaced.