Hi Steve,

Is this vehicle only running on 3 cylinders or is it actually misfiring? Does the misfire occur across the whole rev range? Is it possible to scope the HT or ECU signal on cyl 1? I sometimes attach plug leads to the coilpacks and use a timing gun to verify misfires. Remember also the misfire could be due to the engine or injector on cyl 1. Compression check and exhaust emissions can also give you a pointer.

Regards

Pete M