W126 560SEL New to Me - 2 issues

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All -

I perused the archives and couldn't find either of these issues specifically as related to my 560SEL:

1 - Rear Suspension - Seems to ride at correct height and not bouncy, but sags/squats on hard acceleration..? The accumultors are new.... Not sure what this could be, or if it's normal? Doesn't seem like it. Fluid is there although below the reservoir retaining spring.

2 - ABS Light - On every time the car is started UNLESS you hold the brake and immediately shift into gear after starting, which produces a shuddering noise/feeling and the light goes off..... Weird.

Any advice on either of these is appreciated.

Thanks!!

-Reed