I bought a 1996 legacy 2.2l for my mom, however I am yet to figure out it's horrible missfire issue, if I am on the gas easy with little to no load, or in neutral the car revs fine with no bogging seemingly, however once I put it in drive and start driving, you cannot go past 20-30% throttle without it bogging and misfiring. I already replaced the spark plugs, wires, air filter, timing belt, water pump when I got the car for her, (the issue was there before the timing belt) I did some tests and the o2 sensor was varying hugely in its output voltage, no idea if thats ormal but I had a new one laying around so I replaced it anyways. The problem is still there, whether its hot or cold. I just replaced the o2 sensor (in a foot of snow lol) and now it will even backfire every now and then. SOOO my only idea now is a clogged cat, it rattles like crazy and Ive heard a clogged cat could cause bogging, any way to test it? Also would a clogged cat be a cause for slightly more than usual exhaust smoke? Any help greatly appreciated, thankyou