Porous ignition cable

Hello dear members, heard today from my workshop that the ignition cables that control valves/cylinders at the engine ( 320SL , year 1994 , from 2002 Prinsgasanlage ) , must be renewed . The cables that go directly to the engine to the individual cylinders are crumbling, porous and thus not ignite among others 4th and 6th cylinders , restless running etc. Had any of you heard of this cable problem – normally age-related to the R129 or exception ? Or is it a special that by the operation of the Gas system has been created (higher temperatures in gas operation)? What recommendation can you give me to prevent premature cable wear again? Ask for your experience/ advice/help Thank you! Yeilis (new member)