Changed the rear O2 sensor today, rerouted a couple of vacuum lines to get rid of the MAP/Baro code. Both codes are gone, stumbling is gone, car is running great, but now I'm showing 0701 and the check engine light was/is flashing, not flashing, flashing, not flashing, etc. What's up?

go to auto zone and get a free engine check up. i would do that or just wait a couple of days to see if your light goes off permanently.

flash cel means its critical, and that the cat of the car can be destroyed.

flashing Cel means multiple mis-fire.