Yep its your proxies, my best bet is shared proxies from buyproxies.org. $75 for 100 private proxies is a steal. After getting private proxies, harvest yourself some good old public proxies.
You use the private to back everything up and use the publics asap. Get around 100-200 publics ONLY. If you harvest thousands of public proxies like 5k of them the first 3000 will be dead before you even use them for harvesting. What I suggest you do is harvest 200, use 100 privates. While you are scraping, harvest new public proxies and replace them as you use them