You need to switch out to a “progressive secondary linkage”. Holley makes two different ones. On my 454 with a Holley Terminator X Max Stealth with a 4150 throttle body I ran into issues where the secondaries would stick when coming down to an idle. I switched out to the adjustable linkage and then and now they open at approximately 51% tps and close much better.
Once you install it you go into the software and turn on progressive secondaries and set it to the TPS where they open.
Progressive linkage kit
