The only sure way to tell if your air pressure is right, is with a pyrometer. Taking temp. readings from 3 spots across the tire. When matching up side to side, it can tell you if your getting equal loading. I realize not everyone has one of these, but I have heard that the trigger pull lazier ones for the kitchen work ok, plus they are cheaper. You will want these readings as soon after a launch as possible. Have someone waiting for you at the turn off. You want even temps across the tire and even side to side.
There are several things that can load then unload your rear. Most of the time it has to do with power to traction.
The first situation is not enough power for traction. You will have stored energy in rotating mass of engine and fly wheel/ converter to load it but as soon as stored energy is disapated, your not at high enough RPM to create enough torque to maintain it. (dead hook) The fix for this could be as easy as launch RPM or stall speed or even a rear gear change.
The second situation is too much power for traction. This is basically buzzing the tires. The exact opposite of the first.
The sweet spot is in between these two.
Both cases are a balance between power and traction. Given that you have tires optimized with size and air pressure, the trick is to speed up or slow down wheel speed with gear or launch RPM. The converter plays a big part in this. Getting air pressure right to keep from distorting tire contact patch is first on your priorities. It is true that too much separation can distort tire and can be tamed wit IC settings and shocks, but before you go that way try getting air right first, then if you have to change settings you may have to change tire pressure again, but not much.