1 month ago, we installed a nitrous kit and a higher carb spacer....... ( the nitrous hasn't been activated or used )...... Here is where the problems started.
Seems like it would have been worth removing the taller spacer/nitrous kit and putting it back to how it was when it ran good.
In your other thread there is mention of crossing the line at 7200, 29” tires, 4.11 gears, and 127mph.
If all of that is correct, then the converter is slipping 20%....... and is junk.
