I have a 1997 cobalt 22 ft. Has a 7.4 liter. Engine model number is MCM7.4LXMPI. It is multi port injected and has electronic ignition. Engine fires and runs fine. Runs great till 3000 to 3200 rpms. Then just flattens out and has a heavy bogging sound. It does not misfire so i dont believe its...
