ORIGINAL: Casper98GT

<--- If that were true we ( our dealership) wouldnt have spent a few thousand on the WDS, we would have stuck with the NGS. lol. How about this DAN.... Say youre Mustang has a multiple misfire, but not misfireing on enough of a percentage to set the Check engine light? What do you do then.... take a wild guess in the dark and make the customer pay 100's of dollars while i replace coil after coil seeing why youre stang hesitates? I think not. lol Just plug in the WDS and use the powerbalance test and find out what is misfiring. Also you can check the coils, wires. So yeah, you can use a machine without a CEL.

I would say maybe IAC. I havent replaced mine yet, but it does start then die every so often.. I know the symptons of an IAC. They are a huge downfall to FORD. Also DPFE. But i doubt thats the problem.