1999 Civic EX engine: D16Y8 Automatic Transmision 135K miles
It all started while driving at highway speeds the car would start stumbling.
Gradually it got harder and harder to start the car when cold.
No problem restarting it though once warm.
What's been changed: fuel filter, spark plugs, cap/rotor, wires.
By priming (turning the key to on without engaging the starter) until you hear the main relay click off and repeating this priming for 15 times or more, the engine starts without much of a problem.
Also keep in mind that the engine bogs down when the accelerator is applied heavily. When you floor it, the engine seems to want to stall.
What can be wrong?
Possible fuel pump filter bag clogged up,
fuel pump pressure (bad pump?),
fuel pressure regulator.