Excessive bounce

[Utah2020ST]

Hi everyone, my name is Michael I own a 2020 ST with 68k miles on it. Recently ran into some issues with my ST having an excessive amount of bounce while driving 40-70mph. Ive noticed it goes away once I hit 70+ and once I get onto newer paved interstates. I Initially thought it was a bent wheel, failing rear shocks or just low quality tires. So I went all in and replaced wheels, tires, and rear shocks. I still have this problem. I already check all suspension components and nothing has excessive movement.

Any ideas?

 

[Combatvet]

Time to check the springs, is it lowered? Could be bad shocks, low quality tires like you mentioned. Too many variables.

 

[Utah2020ST]

Time to check the springs, is it lowered? Could be bad shocks, low quality tires like you mentioned. Too many variables.

I went with the PIU rear shocks. Didn't really think of the springs. I have tires road force balanced and even moved to a 20" rather than sticking with the 21"