Hope someone can help as running out of options. Have a sporadic misfire and engine light code, mostly on motorway, misfire is not severe and can accelerate through it. Autoexposure electrician says all electrics are good and everything operating within normal parameters so that rules out plugs, coil packs, sensors. Had garage take of inlet manifold (pain in ass job!) and there was only minimal sooting and injectors clean so that's not the issue. Have put fuel cleaner through system (Sea Foam SF16) twice and no change. They said it's either ECU playing up (new ECU😢) or leak somewhere and have therefore suggested I start with getting a smoke test done which won't be cheap. Any advice appreciated