After adding fuel additive, SUV performed badly
I would suggest checking the EGR valve (https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-exhaust-gas-recirculation-egr-valve) (exhaust gas recycle). Inside your motor, temperatures can reach 2500 degrees. This is when the EGR valve is needed. When engine temperature is slightly cooler, such as when idling, the EGR valve...