Engine/exhaust system 'chugging' - Misfiring? Exhaust leak? 2000 Subaru Outback

The car had no accelerating power and it was well overdue for new spark plugs and wires. I just replaced them and it’s doing much better, however, the engine seems to be shaking a bit when I start it/idling, which is making the entire car shake some too ( the seats, car shifter, etc ) . It’s been awhile since I’ve also replaced the air filter too, which I obviously should have checked but haven’t yet. When I replaced the spark plugs, I noticed there was a minor amount of engine oil on the spark plug wires, where they connect to the spark plugs; more notably the front 2(of 4), left and right. I also just changed the oil and there was no oil loss really, other than any minor amounts that get burned off through the miles.

The exhaust manifolds ( y-split ) are okay, but one of the nuts seems to loosen over time, causing a minor air leak there and makes it a tad noisy. Near the back half of the exhaust system, there some water dripping at one of the connections, and at the tail pipe the exhaust smoke is chugging and isn’t consistent sounding.

Does anyone have ideas as to what is still causing this engine shaking and the chugging noises from the exhaust system. The ‘Check Engine’ light is on, due to other repairs I know I need to make, such as an 02 sensor and fuel level sensor; however, lately it has started blinking too.

Thanks for your help and time.

Oxygen sensor is a critical component of the fuel system and a bad one can cause serious running problems and wipe out your catalytic converter.

In the case of your car I would have already replaced the plug wires and coil trying to chase away the misfire.

Get the codes read and post them - the exact codes rather than vague verbal descriptions. With the engine light blinking you have more than the last time you checked.

Check your fuel pressure.

Yes, the 02 sensor is overdue for a changing and will do that soon. How often should the coil be replaced? I will probably change that too since it hasn’t been since I bought the car(used) many years ago.

Thanks for the advice.

Thanks cigroller, will check those out too.

After getting the codes read and the exhaust leak fixed, clean the MAF with a sensor safe cleaner.

I’ll look into cleaning the MAF sensor too, thanks knfenimore.

Photog016- You do know that driving the car with a blinking CEL will likely damage the catalytic converter?