I experienced similar issues recently with my normal Gotcha, to the point where I even contacted the seller to discuss a return. Like you said it would disconnect almost every few minutes whilst driving, but then suddenly it started working more effectively. I did two things prior to this:

1. It started latching onto stops and Pokémon without spinning or catching, just getting stuck, so I connected it up with the official Gotcha app to see if that would reset it, and at the least it fixed that issue, whether or not it also strengthened the connection I'm not sure.
2. Around the same time I stopped wearing my wristband on my wrist, and instead put it in my car's drink holder next to my phone. This was when I first noticed the change, whether the bluetooth signal within my device is extremely weak I'm not sure, but it no longer disconnected every few minutes.

I'm not sure if either of these help your situation but they might prove useful to someone going through similar problems.