Suburban is running really rough. Like it is missing or something. I took it to AutoZone and they tried to put thier tester on it and the unit wouldn't work. It kept saying it must be hooked up to the car for it to work but it was hooked up. We looked everywhere to see if any fuses were blown but didn't see any. While I was their someone else used the unit and it worked on their car. Any suggestions? I need to drive it out of town tomorrow.
