Tame my 4-speed Stroker....

Sorry Jpar but yes the clutch is slipping.
If it wasnt the wheels would be turning at exactly the mathematical equivalent of the rpms divided by the gear ratios...any different means the clutch is slipping. Its math.

And its ok because clutches are designed to slip some. They have to.
Apparently others agree with me and maybe you don't even know the function of what you installed on your car???