Novak HV 6.5-Issue help needed!

Hey guys, Im trying to run my HV 6.5 on 4S lipo. I brought it off a mate 2nd hand, and its only been used few times-I was there too.. in a deal for a Novak Converted RC8. With either my Hyperion 5500 35c lipo or Flightpoer 5000 25c lipo and tried 2 different rx's I have same issue.

Right, It will work fine for about 2 mins, then all of a sudden it would either stop, or steering will only do like 50% or travel.. and not go.. Until I let off everything for a few secs then be fine.. then maybe happen again 30 secs later.. I have no idea what the issue could be, someone has mentioned to get a UBEC and run that. As it seems like a voltage drop issue-Running a Savox 1258 servo. But, I have no idea.. anyone else have same issue or how to fix it. And seen someone mention run a RX Pack too-Which i dont really want.. please need help asap. I want it running fine for our next club meet-To have a laugh.. and run my 809 properly.. cheers! I hope its simple as running a UBEC.. but doubt it..
Another thing, I tried wiring it like it says for 1 pack.. and nothing happens only esc fan works with seperate rx pack. So put it back to how it was.. which works but has the stopping issue-PLEASE HELP!