1999 Silverado 4.8 Auto Hard Starting

[mooseye]

Hi,

My truck will usually start on the first rotation when stone cold. If it has been driven and then parked, it must turn over for about 5 seconds and it seems to help if I press the gas pedal down once. Other than this, the truck runs great and gets around 21mpg. Not bad for a 4x4. I would like to fix this little problem if anyone has a suggestion. This problem dosen't present if the motor has only been off 5 minutes or less or over night. Other wise it must cool completly, then it will start "first pull". I am guessing some sensor or such, but not really up on these newer models.

Thanks ahead of time for any help.

Randy