What it sounds to me like you are describing is a wheel problem. A violent ground loop just shouldn't be happening on an Ugly Stick with its wide gear and long enough tail moment. I'd check for the following:
1. Are both wheels set up perfectly straight compared to the fuselage centerline? You'd be amazed how much they can be off by and still look fine. Do some measuring.
2. Do both wheels spin freely? Also check if they are able to bind with some side load. If a little yaw on takeoff makes the wheel tilt so they bind against the gear, that's probably your culprit.
3. Is your landing gear actually strong enough? If it's flexing with every little bump, you will never have a good handling plane.
4. Assuming your rudder trim makes the plane fly straight (have someone watch you fly and verify this), does your gear setup also make the plane roll straight? If not, the transition from tailwheel control to rudder control of the yaw will cause a snappy ground loop.

I've had two planes that were a beast on the ground and fixed them both. The first was a second hand Cub whose axles weren't straight to the fuselage centerline. A couple of tweaks fixed it right up. The other was a very poorly built trainer that had right yaw trimmed in to compensate for the roll of a warped wing. As it sped up and lifted the nose wheel, it would take a hard right on the runway. Proper trimming and a readjustment of the nose steering fixed it.