The best riding vehicle I ever had turned into a monster this past summer and it is a pain for me to fix. I live a 6 hour ferry ride and 2 hour drive to a Toyota dealership, or a 6 hour ferry and 1k drive to a lexus dealership.
I am driving to a lexus for a 'holiday' next week ( toyota service was clueless and useless - what a wasted trip..of course it worked then) I live in the Pacific NW and thought the lexus would be reliable, so didn't panic about servicing.

Please help so I get them to fix it!

Random heights while driving. Starts low, creeps up - crazy jacked up after a 15 min drive, so super stiff drive. Light on sensor flashes OFF repeatedly. Park vehicle and it hisses. Drive it an hour later and it is 'bottomed' out - another horrible ride. Slowly rises - light flashing. Great ride for a bit, then super high again. Very random the up and down. Useless on any bumps as a result.Sometimes it stays low for days, sometimes high for days.

What pieces should I ensure they (have to go to Victoria BC) replace/service? Is this any way related to a TSB?

Read on the forum to have the exhaust height solenoid valve replace. Any other suggestions? Is this problem common on 04's or did I just get lucky.
Appreciate any pointers so my 'holiday' is well spent.

 

Sounds like you may have a leak in the air shocks. The system is filling to try to compensate than shutting off. Just a guess.

 

You have either leak of sensors problem. Sensors are around $450 from ebay (pair) and les then 1 hour of labor.

 

Hopefully Mann777 chimes in. He is a guru.