The P32AC-DMs (Amtrak & Metro North) can do 110 on diesel, not electric. They operate on 750VDC 3rd rail in the terminal territories approaching Grand Central Terminal and Pennsylvania Station, where speeds are limited. See: [en.wikipedia.org]. FL9's operated in similar service, and also ran faster on diesel than on electric.

The NJT DMs operate from the NEC 25KVAC overhead, and produce more HP as electrics than as diesels. They're designed to keep up with traffic (including adequate acceleration) on the NE Corridor portions of their runs. The P32AC-DMs are not.

The LIRR DM30s, like the P32AC-DMs, run on relatively low-voltage DC 3rd rail in the electrified portions of their runs, especially into the East River tunnels and Penn Station. Notice at [en.wikipedia.org] the maximum speed and power on electric are less than on diesel - the opposite of the NJT case.