“Sorry read your post again and missed some thing
Yeah I used to just mark as fixed but they keep coming back again and again and again.”
So they are flagged as 404s, you mark as fixed, and then they reflag again?
This is normally because although the page in question has been removed, someone somewhere is linking to it, so it shows up again.
We get it all the time, a business listing that has been removed from the directory, but other websites and pages are still linking to the deleted page. So it shows up again in the Google report. eg:

In this case, the saynoto0870 forum has 6 different links to a page we have removed, but google keeps flagging it:
"Googlebot couldn't crawl this URL because it points to a non-existent page"
Not much we can do about it, and we are automatically deleting pages on a daily basis, so we get lots of 404 Not found errors. If it's because you are removing old content, then don't worry about it. I never bother with the Google URL removal tool unless someone specifically wants details removed asap from Googles cache. Otherwise Google will naturally drop it from the index in around 30 days.
Not much you can do about inbound dead links though, unless you want to manually let people know.
I suspect like us you are generating lots of 404 errors as you have lots of stale content that regularly needs removing, so I wouldn't worry about it. If it wasn't related to content being deliberately removed, then it is showing you that you have a page that can't be accessed.
You do need to check out any soft 404 or server errors though as that cab point to genuine problems.