1988 Oldsmobile Ciera lost power

Hi, two months ago I had a loss of power driving down the road. I changed the catalytic converter, fuel filter, spark plugs, wires, and finally found out my problem was my center coil pack.
Yesterday, I had the same sudden loss of power, so I went and picked up two more coil packs so that I'd have a full set of three. I replaced these and still have the loss of power, I checked the middle one I had originally changed and it was ok too. I checked all the plugs and they looked fine. Do you have any suggestions on what I should do next? Thanks in advance!