Why does my 2002 Chevy Impala now drive very slow.

What is your question?

My 2002 Chevy Impala is now driving really slow as push down on the gas peddle as the light turns to green. Won't go no more than 10 miles as I put gas in it. Drives down the road very slowly. Kind of dangerous going so slow and afraid that other cars will hit me from behind. Sometimes I drive the first lane so my car ca pick up a little speed so I can keep up with the other on the road. It is very frustrating being the slowest on the road. At first I had problems with the car taking off at all. The car will just sit there at light wouldn't take off at all, taken my food off the break and it sat there. I did get that problem fix, but not completely. The car started jerking before taking off, but it takes off, that is not so bad as the car constantly going really slow in busy traffic as I take off at a green light. Definitely too afraid of taking the car on the freeway and highway, because it is a life risk.