05 torque converter lockout issue

[KTenney]

Title should read - torque converter lockup issue

I have a 2005 Dodge 3500 4x4 quad cab dually with 48re automatic, 160,000 miles. Recently when towing around 45 mph and easing into the throttle the transmission will start shuttering right at the torque converter lockup point. Is the torque converter lockup clutch slipping or is this an APPS issue. BD advertises a APPS TPS noise isolator would this help?

Thanks,
David