hi all I've got a 1996 316i coupe,i was driving down motorway the other day at 70mph 3/3500 rpm when my car started spluttering and pulling back,if I put my foot down car took off dropped speed back down to 70 and car cut out and wouldn't restart got recovered,left car on driveway went out following morning and it started first time,after looking online decided to change fuel filter,went through paperwork and receicpts and found out fuel filter hadn't been changed since 2010,took car out on a 20 odd mile test drive after changing filter,had no spluttering or pulling back,took car on motorway the following day and it done exactly the same spluttered and cut out went to restart car and when I looked in rear view mirror I had a flame higher than my boot lid,ive had the car a year,but only been driving it since the 12th of this month as only just passed my test,it's going on the code reader tomorrow but any help or advice you can give me will be really appreciated as haven't got deep pockets for a hefty repair bill,all I've done to car since owning it is a cone air filter and an oval scorpion stainless backbox,car was running fine until I put redex in it and then ended up with the car smelling like mankey eggs from exhaust pipe i'm at a loss to what it might be i'm mechanicaly minded so don't mind getting dirty just want to fine out if this has happened to any one else if so what was the cause of the problem thanks