Usually the rear engine mount (the one under the hood above the engine in front of the driver in a round metal housing) goes on these and causes lots of vibration. You can replace the round bushing for a $20 poly mount and the vibration goes away...also never wears out. Check the ones under the hoods of these cars to see if they're ripped.
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1998 S70 T5 Emarald Green Metallic (125K), 2004 V70 2.5T Ruby Red (45K), Previous Owner of Black '94 850 Turbo Wagon (Sold at 140K and miss her). My cars have been running so well lately they've got me worried.