my 90 lesabre, was off the road for a bit, it is on back on now, I think it may be a dirty throttle body , but here is what it does, idles fine at a red light, stop sign, going down the road doing 30+ just berely on the gas it if fine, if I let off, the rpm'* jump down and back up every few seconds by a couple hundred RPM. It is an abrubt change, goes down and right back up, you can here it, feel it, and see it on the tach going down the road. Anyone ever had this problem? only happens doing 30+, any gear, car runs just fine other than this. Like I said if I am just berely on the gas ALMOST idleing going down the road it is just fine, as soon as i let off this little bit, it starts doing this, hopefully I can get a audio clip in the next couple days, Could this be the throttle body though? thanks for any help on this guys! by the was no SES light ever

Yep mine does the same thing at around 25-30mph its just the trans trying to find where it wants to be. I don't think the electronic trannys do it, but these do. 25-30 is nearly idling and so it thinks you're slowing down and wants to downshift.

No worries.

okay...well it did not start until a few days ago, and it will also do it at 40, 50, 60, 70, 80, 90, 100...etc etc (KM/H btw) went for a highway ride the other day, and it did it at any speed all the way there and it back when i let off, the trans does have the proper amount of fluid

ooh. now that could be a problem. is there any way you could get a video of this happening?

Could be a bad or dirty Idle Air Control valve. There was a service bulletin at the dealer for the 90 trying to stall upon deceleration. Its worth looking into.

Ok well I can't get a video or sound yet...hoping I can in the next few days. Seeing as I have no internet right now, I do at school though. Did some more driving....and if I am just on the gas a very little it does not do it, but being on the gas just a little next thing I know I have to slow done, and then it does it, I have straight exhaust so I can deffinately hear it. The sound is a quick, abrupt BLAH, drops 100-200 rpm then goes right back...I can time this going down the road not on the gas, it goes, 1-2-3-blah-1-2-3-blah, that is literally the sound it makes dropping the rpm, car won't stall out though. I was doing 30 it wasn't doing it also...not till after 40 it seems. Where is the IAC located so I can check it out? whats recommended to try cleaning it with? once again thanks for the help.