Hi,
With the non-lifting blades the small wing on the tango provides the lift so it has to fly pretty fast to stay in the air. I suspect the Tango could also use a larger rudder but it sounds like it's just flying too slow.

If I were to rebuild, I would go with the lifting rotor blades and discard the wing. It flies much slower and handles like a gyro.

Set the booms coming from the top of the fuse to about 12 degrees up. Tip the rotor shafts out about 4 degrees and that will allow more clearance for the rotor blades over the booms. Mount the blades flat and do NOT tip them up as shown for the updated tango. Make the hubs solid so they don't flex. I also recommend the SG6042 profile blade as it provides more lift then the Clark Y. Have the tip of the blades swing even with the side of the fuse.

If you can, increase the size of the rudder it will provide more control. By keeping the rotor blades close to the fuse helps the rudder control.

Set a positive pitch on the rotor shafts of about 12 degrees, relative to the thrust angle and you should should have about 4 degrees of down thrust on the engine.

If you need more information please let me know.

Good Luck,
Phil