Transmission shuttering on a 2005 toyota tacoma

I have a 2005 toyota tacoma pre runner 2 wheel drive. The truck has approx. 187000 miles on it. for about the past year whenever I drive between 25 and 30 miles per hour the truck shutters. this only happens when I’m driving slow; when I’m accelerating past these speeds (i.e. on an on ramp )it does not happen.
My wife found some discussions on line & apparently this is called “Transmission shuttering” & Toyota is aware of this. When I notified Toyota of this they denied any knowledge of this problem & I need to have them diagnose the problem for $125.00.
Has anyone out there heard of this problem & what should be my next move?
Thanks,
Tim