I don't think GPS or any particular app is the cause, but just a symptom. I rarely ever have GPS enabled/on and I've never had the Facebook app installed and still occasionally experience a bout of data drops regardless of what I'm doing on the phone. Sometimes it happens with an app, other times when just browsing the web, sometimes it happens on its own even if I'm not using the phone at all. In either case it's very random and will usually correct itself at some point. Other times toggling airplane mode helps. But ultimately from my experience the best way to minimize the issue seems to be a battery and SIM card pull about once a day (something I do anyway as I swap out for a fresh battery, never charge them in the phone).
As I posted earlier in the thread, I still think Droidforums.net posted some really good info as to what's going on and options to consider:
http://www.droidforums.net/forum/dr...s/218137-why-my-lte-device-dropping-data.html
"Why is my LTE device dropping in data.
1) If the device is not staying connected and constantly dropping data it could be a hardware issue.
Solution: Change out devices. Try doing an exchange and if you still experience constant drops you may need to look at swapping to a different handset all together (ie from Nexus to razr).
2) 4g has been working fine but lately I am getting no connection, mms fails, and sometimes calls will not connect
Solution: Swap out sim cards.
3) My 4g works great but out of no where it drops off for 2 mins.
Solution: It is designed that way. Talked to an engineer and the idea is that if a tower gets congested it switches you to another tower. That momentary swap causes you to momentarily lose data.
But that did not happen before. More and more people are buying lte devices causing more congestion. The idea of switching people from tower to tower is designed so you do not lose data completely or for long periods of time. I am playing with at&t lte and I would rather lose data for 2 mins once or twice a day than 20 mins.
But its happening more than twice a day. Call a tech they may need to reset the provisions in your phone to make sure its locking on to the towers. Also as
OEMS learn more about the network they are building better radios and more efficient processors to lessen the time it takes to switch."
Edit: bolded above is probably why newer phones don't appear to be be affected as much. I'd bet they actually are, but are so much better at switching than our first gen LTE Thunderbolts that most don't notice it.