2.2 01 Sunfire Power Loss

Here's some history. The car started missing and stalling, so I replaced the plugs and wires in hopes this would resolve the issue. No go so I took it into the shop and they replaced the coils which resolved the miss. For a month everything was fine then on a trip the car started to miss again, wire vibrated off the coils as the clip was slightly bent. Again car is running fine for a couple weeks, now I have a sudden loss of power. Seems unrelated but thought I would mention the previous work as it is the only recent repairs on the car. There is no miss in the engine and car does not stall or fluctuate in RPM now, it just has no horse power, it has trouble getting to 50MPH, and it seems to not have enough power to want to shift to the next gear unless I let off the gas to let it shift. If I floor it, the car seems to bog. The check engine light has come on with this power loss and stays on. Code reading cost $ in Canada so I haven't had it done yet, but when they replaced the coil they said there was an Oxygen Sensor code tripped as well. I have replaced the air filter just to be sure, and have a fuel filter which I will be putting on Saturday. I have also replace the front O2 sensor and probably will do the rear one Saturday as well if anyone thinks that will help. At this point I am still experiencing the issue so any suggestions would be greatly appreciated. (Other then type less hehe)

Edit: Oh and the gas mileage is crap now which is why I think it's the O2 sensor still.

Well I had the codes tested today and the garage said it is definitely a blocked catalitic converter causing the power loss. It also had engine codes for misfire, crank sensor, cam sensor, and 1 evap code. Some of these may be caused by increased back pressure so I will see if they come back when the cat is replaced. Alaso has a slight leak in the volve cover gasket which is apparently leaking oil onto the plugs and wires, so I will replace the wires and clean the plugs after replacing the gasket. Just thought I would let everyone know the result in case it helps anyone else.

glad to hear you found the problem,thanks for the follow up info

What is the best way to clean the plugs anyway folks?

Use fine sandpaper on the electrodes.

You can wire brush the rest of the plug...

It may be better just to get new ones....