98 Lexus ES300 RPM Problem

I have 98 Lexus ES300 with 77,000 miles. Here is my problem. The car
starts and cranks fine and runs fine usually. But sometime right after
I start the car and it is still in park the RPM gauge drops to the last
line before 0, but the engine is still running and you can feel a very
slight vibration or rough noise, very hard to feel or hear Must turn
off A/c and radio. When you put it into gear say D the car doesn't roll
forward until you press the gas. Usually with automatics the car rolls
forward a bit even with out pressing the gas. If I step on the throttle
a few times or just ingonore it and drive say for 30 seconds like
leaving a parking lot. Then the idle goes back to normal around 1 or
the line right below 1 and the car is fine. It so far has only happend
right after I drive and try to restart the engine, like quick stops for
5 min breaks. It has never happend yet when the car has sat for a while
right before starting it like in the morning.

Does anyone know what is causing this problem? Is it expensive to fix?
Is the engion oil sludge?

Thanks

<integra144 RemoveThis @gmail.com> wrote in message
news:1150933739.021577.206790@b68g2000cwa.googlegroups.com...
>I have 98 Lexus ES300 with 77,000 miles. Here is my problem. The car
> starts and cranks fine and runs fine usually. But sometime right after
> I start the car and it is still in park the RPM gauge drops to the last
> line before 0, but the engine is still running and you can feel a very
> slight vibration or rough noise, very hard to feel or hear Must turn
> off A/c and radio. When you put it into gear say D the car doesn't roll
> forward until you press the gas. Usually with automatics the car rolls
> forward a bit even with out pressing the gas. If I step on the throttle
> a few times or just ingonore it and drive say for 30 seconds like
> leaving a parking lot. Then the idle goes back to normal around 1 or
> the line right below 1 and the car is fine. It so far has only happend
> right after I drive and try to restart the engine, like quick stops for
> 5 min breaks. It has never happend yet when the car has sat for a while
> right before starting it like in the morning.
>
> Does anyone know what is causing this problem? Is it expensive to fix?
> Is the engion oil sludge?
>
> Thanks
>

Unfortunately, nobody can tell you what is causing the problem without
actually looking at the car, but there are some things you can check, and
engine oil sludge does not usually cause the symptoms you are describing.

I would check the idle air control (IAC) valve and the mass air flow (MAF)
sensor first.
--

Ray O
(correct punctuation to reply)