I wouldn't fly until you can get the idle to be constant. Like jaka and others have said, sounds lean. Keep richening to see if that stops it. Don't worry about how far you go out on the low needle. If it fixes it it fixes it no matter where it is. BUT if no matter what you do to the low needle, it still doesn't fix it, then you need to look for an air leak. Try to go as rich as possible on the low needle to get the idle constant. It's easy to try and won't hurt anything.