Guys, I need your help. I own a 2002, EFI, A/T Lancer. I encounter this problem only in the morning, or when I don't use the car for more than 12 hours. Also, my battery is new (barely 4 months old).

Here's the problem: the car starts with just one click, without a problem. However, after about 5 seconds, idling starts to drop until it dies down. Once I restart, I still need to step on the gas for about 30 to 45 sec for it to sustain proper idling. After that, I'm good to go. This problem does not happen when the engine is hot. This only happens in the morning, or when the car is not used for more than 10-12 hours.

Need your opinion on what I should check for when I bring this to a repair shop. Thanks in advance!