[3400] Misfire at closed loop transition?

[Kardain]

So the Sunfire started doing something new... at the point where it hits closed loop, there's a bad misfire and idle surge (between 500 and 1500 RPM). If I shut the car off when it starts doing that, then restart it, all is well till lunch time (about 4 hours later).

Could a faulty front O2 sensor cause this (not throwing a code for the O2 though)?

If it helps any I don't have a rear O2 installed.