Gas smell rough idle

I have a 1998 Honda Civic dx automatic 4 cyl with 160000 miles. I drove around all day with no problems. At the end of my day I got in my car to go home and started driving. In about a hundred yards I noticed a gas smell coming from the vents and the car started to lightly shake and buck. Simultaneously the check engine light started flashing continuously. The car feels like it is going to stawl as I slow down and when I am stopped. I have read hundreds of forums tonight and have not found anything exactly the same as my problem. Any information you might be able to provide would be usefull.

Sincerely, Anthony J Fonseca