Recently, have hade severe sputtering & missing
This situation does not occur until the engine heats up. It runs like a top until you have drove about 5 miles & then it starts sputtering. In idle you can watch the RPM's bounce around. It runs better when not applying much gas. Bad during middle of the pedal & better when giving alot of gas but still
misses. I have replaced the plugs & fuel filter & given a couple of treatments of injector cleaner.
Sounds like a air/fuel ctrl problem. When the engine is cold the ECMruns on a preset program when enrich the fuel to help warming out. Once it read coolant temp reach normal it goes into close loop and let the sensor carry on it s designated duty. Have ur mechanic chk ur mass air flow sensor with an oscilliscope. Chk O2 sensor waveform. Also do an ignition scope KV chk. If ur mechanic are equipped with 5 gas analyser then it wil be really easy to nailit dn if ur problem is cause by lean condition when it act up. NOTE: Only known fuel system treatment is by using a fuel system engine decarbonize machine such as auto 2000, motorvac
which proven in the industry effectively. Cans of additive to the tank in my opinion is more psychological than mechanical