E30 Zone

My 325 has developed a 'stutter' as a friend put it.
It's most noticeable under part throttle and motorway speeds, the car shakes and feels like it's struggling. There is also a smell of petrol when you get out of the car, it's not very strong but it's there.
Because of this i'm thinking it might be overfueling but have no idea how to find out or how to go about sorting it!
Any help will be much appreciated.
Simon

Theer are a few possible reasons. All are covered here:

http://www.e30zone.net/e30zonewiki/index.php/Intake

stuttering might be your ht leads, fuel smell might be the rubber pipe on the inlet leaking out, or a leak somewhere else, check your plugs to see if its overfuelling, if not i used to get a stutter and a jerk on the freeway, changed my leads stutter stopped changed the rubber pipe to the fuel rail sorted fuel smell,