Hard To Start After Warmed Up

[Neejay]

The car cranks right up on cold start. Once I drive around and/or it reaches normal operating temp, turn the car off, then immediately try to turn it back on, it doesn't start until I blip the gas pedal.

Any ideas? (RB25)

[blind_elk]

Water temp sensor.

Cold Start Air valve.

[Neejay]

Water temp sensor.

Cold Start Air valve.

ECU coolant temp sensor was also mentioned by someone else.  Thanks.