Es300 Engine Slightly Racing At Idle

[lexuses]

Folks, I've got a '93 ES300 that bumps up and down about 200 RPM at idle when in gear. If I put it in park it seems to settle to a normal idle range. Any idea what might be causing this? It runs great at higher speeds and I don't notice any hesitation, however the idle thing is really annoying.

Also, I remember seeing a post recently about a rattle noise in the front end at low speed. Can someone provide me some info on this or point me to the post? Thanks in advance.

[dropspace]

can you tell where the rattle is coming from?

i had an annoying rattle that i could hear only at low speeds and it turned out to be the wheel caps being loose. I just bent the metal brackets on the back of the caps out and pounded them back on tight....

[SW03ES]

That may be a normal characteristic of the V6, mine doesn't idle steady all of the time when in gear, and its brand new.

[squarehat]

Two things: one, this is especially noticeable in Lexus V6's when cold. Second, is your climate control in "Auto" mode? The fluctuation in RPM could be simply the result of the A/C compressor engaging/disengaging as it deems necessary.

[Latoilette]

can it also be faulty PTU connections or maybe IAA unit?

[lexuses]

dropspace, the rattle is coming from the front end. it could be the caps. i'll take a look at them based on your suggestion.

sw03es/squarehat, it used to idle fine, cold or hot. the ac does not have to be on for this to happen.

latoilette, can you elaborate on the ptu and iaa? i am not familiar with those.

thanks for all the replies.