2002 Dodge Intrepid

Shakes or Wobbles problem
2002 Dodge Intrepid 6 cyl Automatic 133652 miles

my car had been chugging. When I do a rolling stop or not come to a compleate stop my car will sometimes start to chug, when it gets to about 20, 30 or 40 MPH. If I let off the gas it will stop, and if I keep pushing the gas it keeps going but will stop with in 20-30 secs. It has stoped running on me twice, when I was driving. The check engin light came on about 5-7 days before it started to chug. I was thinking that I was my fuel pump, or my spark plugs. I change the plug in november 2008 or 2007. The fuel pump has never been replace. Can you help me with what is going on with my car please.
thanks
sam