i got gas at a local gas station that i think was bad the car spudders between gears like it wants to cut off and it started as soon as i left after putting the gas in i have tried the gas antifreeze stuff as well as the stp treatment for it and it still does it , i have a trip planned soon where i will be driving 400 miles in a week this problem has been going on for a month already and im on a tight budget i have a 93 ford thunderbird could it be a different problem caused by the gas it seems to do better when it is colder here i live in atlanta any suggestions?