I've heard many have head issues due to detonation from the Postal Service requiring them to use the fuel they are not rated for. Personally have seen almost all of them having bad right front struts and mounts (surprise), some severe coolant and oil leaks, sliding doors falling off, and turbo/vac issues from entirely clogged intake systems (VMF doing zero maintenance).
The Metris isn't a bad vehicle it's the abuse and absolute neglect by the VMF that is doing them in. Lots of other applications commercial, livery and as RVs you see them with 200,000 miles or more and they are fine but that is because they are maintained.