Ever since I pumped gas about a week ago my car feels as if though it has lost 20 hp. I thought I may have got a bad batch of gas but I refueled a couple of days ago and I still have the problem. The car does not feel as strong as it used to be and it does not pull very hard in 2nd or 3rd gear even at high rpms. Can anyone give me any ideas on where I should begin looking? Thanks.