98 GT, stock under the hood when I got it last fall. Added CAI, ran fine. Added aftermarket coils, ran even better than before. Just tried to install new plug wires. Found out the hard way they were the wrong length , so had to put the old ones on. Had no diagram, so got one off the internet. Car would sputter but not start. Got CORRECT diagram off the internet :angry4:, car fired right up. That was yesterday. Today, wanted to take a drive. It ran rough once in gear and popped a bit in the exhaust. I checked the wires with an old inductive timing light - all flashed, but some only near the plug and not near the coils. ????? Got old school tester out, goes in line between the coil and plug and flashes on each pulse. Had to put it at the coil end because I couldn't get it to all the plugs, but all flashed. The backfire indicates to me that a cylinder is getting fuel but no spark, but all the plugs seem to be getting spark. Now what???????