Yesterday I was driving and going onto an on ramp that is slightly elevated. I was in 2nd gear approaching 5000 RPM just about to shift to sixth gear due to the speed limit of 50. It was at this point the engine began to sputter and go all the way down to an idle and the check engine
light began flashing. I quickly put it into neutral, while the engine barely remained alive and when the engine light stopped flashing the car regained it's normal idle and I continued to drive the couple miles home. When I got home I checked the DTC code with my tuner and nothing came up, I also let it run for a little bit before going to bed. Then this morning I woke up and let it run a bit and then checked again for DTC code and nothing. So I returned the car to it's stock tune and again checked the DTC and again nothing. It was idling normal so I decided to drive it to school. It ran fine on the way to school and I even revved it up to 4000 in my drive way to see if it would misfire again, it did not. I am unsure of what to really do or if anything is wrong. The car is running fine it has seen less than 10 miles since the misfire last night. Any help is appreciated.
UPDATE: the check engine light now comes on after 15 seconds of turning the key on but not starting the engine. The check engine light flashes 8 times then goes away. Still no engine light when I'm driving. However, I've noticed I'm only getting 14-15 MPG and the exhaust smells gasser then usual.
Mods = Bama SCT flash tuner, Borla Stinger S type mufflers, and an Air Raid CAI