Possible Rpm Problem?

[mwang]

i've had my 2001 Is300 for about a month now and as of late it seems like my rpm will drop very low after i drive anything over 6-7 miles. whether or not i am on the throttle the whole time or am just taking it easy it still seems to fall very low when i come to a stop. any ideas on what could be wrong or is this somewhat normal? by the way it drops to somewhere around 400 to 650 rpm (between the first and second notches on the rpm tach). thanks for any help...

[Lexus300Stock]

is it idling okay???

[smooth1]

It's allways hard to diagnose issues via the boards. I would try resetting the ECU first. Just unplug the negative terminal for about 20 mins. then reconnect it. See if the car relearns idle correctly. If not, keeping in mind that the idle is controlled by the ECU, you may have a vacuume leak. So next I would check all you throttlebody vacuume hoses lines. Make sure one of them haven't come undone or cracked etc. If it's not that, then you may need to take you throttlebody apart and clean it out. Make sure the butterfly is opening and closing all the way and freely. Also make sure all the hoses are connected to the air intake line and especially the crank case breather tube.

[mwang]

thanks i'll try to unplug the ecu first and then go from there..... thanks again...