I am trying to do something that appears to be simple, but I can't figure out a way around it without breaking the rate limit.
The first API call I'm making is the get a user's friend's IDs.
$friends = $to->OAuthRequest('http://twitter.com/friends/ids.json', array(), 'GET');
That returns a huge string with IDs. In my case, I'm following 1035 people, so I get 1035 IDs.
$friends = explode(",",$friends)
This gives me an array with all of their IDs.
But how do I pull the user info from all 1035 of those people without breaking the 150 API-call limit?
If you are trying to get more information than just the IDs, then consider statuses/friends, if the user you are looking up is protected, you will need to auth, which I believe you are doing anyhow.
Why are you requesting only a list of IDs?
While you still may run into the rate limit, you'll get a lot further if you request all the user data for friends.
Maybe you could try the statuses/friends method?
Use the status/friends method and set the count=200 so you can get more than the default of 20. If you need more, use the page parameter to paginate through. The XML format provides a lot more data than RSS.
Look at the API docs (footer links).