I have been having the same problem with brief gps signal lose on my note 3. I removed the case and it behaved the same. BUT, yesterday traveling in NJ I had the usual issue driving for 45 minutes and lost signal about 6 times. Before the return drive the next day I powered off the phone and turned it back on then started the 45 minute trip. I had no gps failures, same route. Not sure if that fixed it or was a fluke. I'll keep experimenting.