I found this article. I might try some of the tips.My rear damping was up a bit high.
Handling Guide | RACING ON THE CHEAP
Instability under hard braking: car wants to spin
• Excessive rear brake bias
• Insufficient rear droop travel
• Wildly uneven corner weights
• Excessive rear damper rebound force
• Unbalanced ride/roll resistance – too much at rear
• Insufficient rear camber (usually in combination with one or more of
the above)