Vivian sent me a few tunes several weeks back and all worked except the tune for fuel economy. Very sluggish, no power. She thought the file may have been corupted in the e-mail and re-sent. I installed it when my engine was warm and all was fine. I started the truck the next day with a cold engine and it was really sluggish again with no power. Matter of fact when I tried to pull into traffic it couldn't go over 35 mph's. I pulled off to the side and let traffic go by. Once clear I got back on the road and it very gradually made it up to speed. I re-installed the street tune and all was fine. Any suggestions? Like I said, when the truck was warmed up that tune worked.