well heres the deal about a week ago my cars ses light started flash and my engine stumbled whenever I would step on it. I have a scanning tool and ive been waiting for the chance to plug it in whenever the light came on. yesterday the light flashed and then stayed on so I scanned it and came up with a misfire in cylinder 4. Now i put all new plugs and wires about 25k ago but I inspected the plug and wire and they looked fine. I replaced all three coilpacks cleared the code pull out of my neighborhood twice and nailed it(Just to test it I dont usually drive fast) and the cars ran and idled the best it has since I bought it over three years and over 75k ago(car has 126k now) went out with my lady and drove all night winding it up every now and again just to test it and the car was just fine. I go out this mornin to run some errands. I was on the highway went to pass somebody and once again the car stumbled and the ses light flashed. Im thinkin ignition module but not sure. any tips would be appreciated. its a 04 gt 3.8na