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Check your exhaust system. I've seen symptoms like these several times.
I wonder, does it bog down when you romp on it at speeds below thirty, but not at speeds higher than that? If so, the car is capable of enough acceleration at low speeds that something may shift and plug your exhaust, but at higher speeds you don't have enough umph to cause this problem. This happened to me once when a catalytic converter had a chunk broken inside that would plug up the outlet.
Backpressure from anywhere in your exhaust can cause smoking, loss of power, and could definitely goof up your O2 sensor readings. You also said the exhaust seemed noisier? Sounds like another exhaust symptom.
I've seen plugged cats, broken cats, pinched pipes, rusty mufflers, un-packing glass packs, and carbon fouled flame arrestors all cause plugged exhausts. They all ran great at idle, and some of them ran pretty well most of the time, but they all ran very poorly sometimes. ...and they can be very hard to diagnose. Ever flow-tested an entire exhaust? How about while it's being bumped and jostled? Yeah. Me neither, but that's what it'd take to test for these problems. Ya might just run straight pipes for a day and see if that fixes things.
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