I own a similar vintage/mileage vehicle, there are three recurring issues I've seen on the forums (do some searches for details)...
(i) Harmonic balancer can fail, consider replacing with latest rev part.
(ii) Transmission - do change oil (as noted by others).
(iii) Cabin air filter (paper), if it get's too dirty it may cause the fan speed control to overheat and fail. This weakness has been addressed in a new revision to the speed control and motor, so if you have the original design and it fails you'll need to buy a new motor and controller, i.e. expensive.
Generally the e430 seems to be a solid vehicle.