I was successful in slowing my previous car down from the 9.90 to the 10.90 class. The car full out would run 9.76.
Anyway I had a 5000 stall too so I used a combination of removing throttle, lowering my shift points to 5300 from 5800 and setting my 2 step on the stall to 2200.
In 9.90 it was a .400 pro tree so coming off the 5000 converter as ok but when I switched to the 10.90 class the tree was .500 so lowering the 2 step to 2200 not only slowed the car reaction time it also slowed the et.