Umm i'm new here but i have a 1996 mustang v6. From the day i got it i saw the check engine light on but didnt pay it any mind until it starts flashing. When it flashes the car bubbles you can hear the difference in performance through the exhaust. I took it to a mechanic shop and popped the hood only to discover that the EGR valve was disconnected and had a screw at the end of it so they took it out and connected it when i went to start the car it struggled to come on and struggled to idle so they disconnected the EGR valve again and started it and it easily came on but still the check engine light was flashing so they put the computer on it , about 6 codes came up .The first code was low EGR and the other all had something to do with that to (thats what the guys at the shop told me). The car has an after market fuel management system but i don't think that's causing any problems. Any help would be greatly appreciated.