1998 Oldsmobile Aurora

Smells problem
1998 Oldsmobile Aurora V8 Front Wheel Drive Automatic 122000 miles

I put gas in my car about 2 weeks ago and then my car missed for about a week, It did fine after that for about 2 weeks but like an stupid idiot I stoped at the same place again and put gas in again and now it is idileing rough and smells very strongly of gas I did try putting gumout in and a full tank of 91 octane but to no avail(help) The service engine also stays on all the time now.
February 6, 2010.

Have the computer scanned for code/s-you have a problem within the engine management system that caused the CEL to turn on-This is your starting point of diagnosis, finding out what's going on.

Feb 6, 2010.