starting problem

[838KGC]

I have a 1997 Infiniti I30t with 148k miles. It is running prefect until 2 month ago. It is hard to get the car started.

The car cranks normally every time when I turn on the key.

The car engine will shut down after starting. I have to step on the accelerator and hold it a little while and then it will be running as usual.

It is relativity cold/warm start. This happens in a cold start, but after running for a while or warm start, it is start as normally.

There is no codes, no check engine light.

It runs great once it starts.

I have replaced the knock sense and the air flow meter sensor, but the problem still exists.

Can anyone give me some advise and let me know what is the problem for my car? Your help is highly appreciated.