Jeff Evans in his EvoX tuning videos says to set some of your Fuel Compensation first column values to about ~20 (aka 20% fuel) to stop rev hang on throttle off. buy his tuning guide video for $49USD a month for all Evo Tuning videos. he explains it in there.
I find it hard to believe it is a clutch issue, but can you rule that out in 10 seconds, by just driving, and then shift to Neutral (clutches off), even lightly touching the brake pedal will open the clutches.
clutches are open when foot is on the brake. it is a mandated safety thing so that if your cars throttle drive by wire gets stuck on full throttle, you can save your car and occupants using the brake pedal.