XemodeX offers a permanant solution. It is less expensive than an ETM from Volvo that is guaranteed to fail. Google XemodeX. Google Don Wilson and ETM.
There is alot of information on Matthews Volvo Site.

I put one in my car. It is a shade tree mechainc level job.
The difference is like night and day. Hesitation and surging are gone. Uneven idle is a thing of the past. You need to make sure everything else is right so you don't mistake the ETM for another problem.

The Marelli ETM fails 100% at 100K Miles. The design uses thin film pots where
the wiper wears out the carbon tracks.

XemodeX replaces the thin film pot with a Hall Effect Digital Angle Sensor. No contact. Nothing to wear out.

-VolvoJoe