In my specific case, I was calling a WCF service that used LINQ to retrieve data from a database and return as a LIST of LINQ objects. When I ran 85 records, it would run, but when I ran 90 it would not, so I knew the issue was size related.

Sometimes, you might need to run a full WCF trace (on both the IIS web service, and the client).
The XML in this article will do that and discuss how to view it.