OP solved it, closing

Close enough, but you missed this part If the **final result** is longer than 140 chars it must return false.

That's a problem with your code, not a kata issue, you only test match doesn't return null and then you work with the original string. While chaining methods seems nice, it makes more difficult to know where your code is wrong. Only chain when you're sure about what your code does.

Because your code is too slow for big inputs:

Take a look at performance: some lists have thousands of elements.