PHP: Using remote proxies - Unreliability issues

[krt]

** Background Info **

I have a function that fetches content from a page using a random remote proxy. The proxy list is updated daily and there should be no connectivity issues. If a proxy fails $contents returns false and the calling page decides how many times it should retry fetching that page with a different proxy. That is all fine.

** The problem **

The function fails too many times, The calling script reports several "Too many proxies tried" yet a fraction of pages are fetched successfully. Can you suggest a possible cause for this?

Any help will be greatly appreciated and hopefully repaid :)

** The PHP code **

I have removed possible culprit functions that set off the POST data filter here to no avail.

Code can be viewed here:
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