The other thing I don't do is manually set my difficulty. I noticed others here are doing that, but is it necessary? My rigs range from about 800 MH/s to 1.8 GH/s.
You are the third one in a row, if you read the last 3 pages. This problem is caused by the fact that BitParking sets the default difficulty to 16, which is too high for GPU/FPGA mining. You should use "d=1" or "d=2" as your password to set the difficulty lower. This will avoid inactivity timeouts and stratum disconnections.
Even though my rigs are 800 MH/s to 1.8 GH/s, my total farm is 23 GH/s. Is it still advised that I change them all to d=2, or does it make a difference if my entire farm is 23 GH/s?
Still seeing the problem, but haven't changed any difficulty settings yet. Also, running cgminer 3.1.1