've just made a discovery that may be a big factor in my problem. Last January I bought a few domains that were in my sector that had some backlinks. I then forwarded them to my domain. I never really investigated them at all. Now I checked one of them via ahrefs and it appears it was being used for all types of spam. All the keyword anchors are classic spam text. What I did was forward a black hole of a site to my own. I bet google penalized my for it. Last month I dropped the forwards and deleted the domains from my account. My question is, does anyone have experience with this. Will google forgive me and generally how fast? thanks!
Domains that you bought, do they now return http 200 or 404? I am asking this as you said you deleted domains from your account and I am not sure if you mean Google Webmaster Tools account or your hosting account.
How big were domains that you bought that were previously redirected, i.e. how many pages?
How was previous redirect implemented, page-to-page or all pages from a domain you bought to one page (home page?) of your main domain?
ususally those redirects from GD are 302's not as they say a 301. Deleteing them from your GD account has done nothing but lose the domains. Taking the redirect off should have been enough, but I highly doubt a domain with a 800 backlinks is the issue. Domain forward could be a domain masking the post you did isn't clear. Did you ever check the actual header from the domain?