Phew! this all sounds complicated so far. Lets consider the swing mechanics.

An outside to in swing path will generally cause the ball to fly high and slice from left to right (it's not a fade).

The normal fault is caused by the downswing being started by unwinding the shoulders, this throws the clubface over the top and outside the path, it also creates a steep swing plane.

You should start the downswing by rotating the hips and dropping the arms straight down while maintaining the same angle with the wrists that existed at the top of the backswing, this will put the club into the correct position to release it through the ball on the correct inside path and plane.

By doing this and keeping the clubface moving down the target line as long as possibe after contact you will create a powerful shot that removes that slice. One more swing thought is to imagine a clock face on the ball, hit through from 4 to 10 o clock. Finally, keep a light grip and relax your arms and shoulders.

Hope this helps
Brian