Won't stay runnin

[cartech89]

This morning, I went to move my sister's 2000 Sportage up the driveway, but it wouldn't start. I checked the codes and I got a pending code of P1115 and a trouble code of P1624.
I know what the codes mean, but what causes them?
The timing belt was changed in last fall and the battery two weeks ago.
I almost forgot, I can get it started if I push on the gas pedal. It will stay running as long as I keep some pressure on the pedal.

[Mike70]

Try cleaning the IAC valve. If it is stuck shut, the engine won't get enough air to keep running.