I recently made the road trip from Brooklyn, NY to Ocala Florida for the 19th Annual Silver Springs Ford & Mustang Roundup sponsored by NPD. The car ran great until I hit Georgia and filled up. I have a Steeda chip and tune from 1999 and was told by Steeda when I lived in S. Florida to always run Premium gas due to the chip/tune. I always have up until this long roadtrip so a couple of tankfulls I ran midgrade and the car ran the same...no problems. I then got gas in Georgia and as soon as I left the station I could tell or thought I got a tank with bad gas. I had run Chevron Techron before I left NY and then when I experienced a rough idle, I put another bottle of Techron in with a tankful of Premium gas. Nothing, the car would still surge at idle from 400 rpms to 800 rpms and rock as if I was playing with the brakes rocking out to a cool song. I also bought a bottle of dry gas to remove any water from my tank and ran 5 complete fill-ups of Premium all the way back to NY and the car is still surging so maybe it's not a bad tank of gas afterall. I don't have any check engine lights on indicating a bad sensor. Any thoughts?????????? Thanks in advance.