I just finished my engine rebuild and swapped in into the car last night. Seems to run fine after it is up the temp, but while the engine is still cold it is a little rough, like there is a miss or fuel problem. The SES light is on with a P0134 and P0155 code. Those codes make sense for the issue, but why is it only when the car is cold?

 

Getting on it a bit seems to help it too

 

The P0155 code has to do with the heating element on the pass side O2 sensor. So I believe it makes sense that the car performs poorly for a while after start-up because it takes longer for the O2 sensor to heat up, right?

The engine gets better as I approach WOT. Anyone thing replacing O2 sensors won't completely fix the problem? Anything else I should look into before spending the $$$