[Optech]

I just bought a 1999 Buick Park Ave. ( not a Ultra). It gives me a code P0301 (#1 cyl eng misfire). It only happens at 4500 to 5000rpm when accelerating onto the highway. I don't normally push it that hard only when I need to. I have changed the wires, plugs,all the coil packs, air filter, and gas filter. I don't know if I should change the control module located under the coil packs ($160.00) or have the injectors cleaned by a shop. I have checked the injectors with an ohm meter and they are very close in ohms to each other. I am new to this forum and any help would be greatly appreciated. Each time I have worked on the car I have erased the code and it still pops up at 4500-5000 rpm.