93 Ls400 Hard To Start In Cold

[andyz001]

I have 93 LS400, 130K mile. I have it regular seviced, runs fine. But recently the car has the problem on cold start.

In the morning, when I start the car, the RPM goes to 1500, then back to zero, car dies out. It seems it doesn't have an idle.

Then I try to step on gas pedal right after the car start (in less than 1 sec), the car is running, I keep the RPM on 1500 for about 10 seconds, release the gas pedal. The RPM returns to steady on 550 idle (the car is still cold).

Usually, the problem goes away right after the car warms up. But I experienced one time the car didn't stay on idle in warm.

I would appreciate if anyone can give me a hint on resovling the problem before I send it to shop.

I'm living in Los Angeles, on average the car get 18MPG.

Thanks.