So you have your max weight set correctly as noted in previous posts
Have you looked into setting the 'Tare Weight' and the 'percent increase for larger packages' under 'Configuration' - 'Shipping/Packaging' to 0?
This will allow the table rate function based on weight to work correctly.
(1:45.00,150:160.00)
up to 1# = $45.00 shipping
>1# to 150#(set as max you will ship) = $160.00 shipping
My store was acting CRAZY like mis-calculations (i thought) which turned out to be actual calculations because any values above zero in the 'Tare Weight' and the 'percent increase for larger packages' seem to really mess up the table rate function based on weight
I hope this helps.
XSSXCS