Hello fellas I'm new to this site . I posted issue possibly in wrong place. I hope I'm now on right track. I bought my c4 in 10/10. due to poor running I replaced opti, icm, coil, plugs, wires, and even maf, to have a fresh ignition system. After initial start had code for brand new, just installed aftermarket icm. Replaced icm, car ran like a champ for 3 months, then had to change icm again. This time no code,went on hunch from experiencing initial bad opti. Car ran like a champ for another 3 months. Again sputtering, but this time bought a delco icm and problem was still there. I formally checked icm through All Data process. AD says icm faulty, only through ignition system check. To be 100, I took to Advance Auto to have the individual icm checked. Their tester said delco icm good. Before taking it to AA I checked pulse from opti to ecm, from ecm to icm, and from icm to coil, all under poor running condition while engine hot, with logic probe( low voltage tester). Pulses had no visible intermittent loss while engine running poor. I checked fuel pressure while under poor condition and fuel pressure at idle was 45-40 and under load driving 35 to 47, within spec. All wires are harnessed and have no contact with engine and have flex cover, mainly plug wire from coil to opti. If you have other possibilities for sputtering, my mind is open!