I use a Deans in my F-16 and get incredible gound range out of it. I have one in my Bobcat, but it has not flown yet due to current climatic conditions ( ie too much snow~~)
If you are using the 2 pc antenna, make darned sure the little piece of shrink wrap does not get caught in the threads...it will insulate the antenna greatly reducing range. If you are still having problems, check for any metal on metal contact.....the throttle linkage is a prime suspect. If there is any, break it up...use a plastic pushrod, or a dubro ball and socket connector.
If you are still having problems, check every one of your servo extensions and the switch. I have seen brand new leads cause erratic behavior, and I had a brand new switch in my F-16 go south...fortunately, I had a dual battery system...
The long servo extensions to the elevator and rudder servos can pick up stray signals, and may need a RF choke (JR makes them) to cut out any interference.


hope this helps.............