engine light code p0133 which was o2 synsor. changed first 02 synsor. on 1996 Toyota Corolla

engin light now flashing car rides ok until pick up speed then act like it is going to cut off the rides smooth again. sounds like it is puttin

2 answers
It is "puttin" cause it has a misfire! Need another scan test to find out why. Flashing light indicates a misfiring cylinder, scanner can tell which one.
Misfire condition from exhaust flow problem. Have cat. converter checked for proper flow.