paulmiles

I have the problem for a year and my mechanic could not fix. He adjust the valves and still same problem. Car runs very good and strong when is warm. But when is cold I have misfire in all cylinder. Now is 30F here where I live.
I think is something related with air/fuel mixture. I replaced air fuel sensor B2 S1 because I have the P1174 code. I also put new EGR valve.
Still after running for 100 miles, every time the car is cold I got misfire.

One thing I notice is my Short Term Fuel Trim B1 is high and is always showing a higher than normal value. Is over 1.0 always. ( picture attached)
Do I have a Fuel leak or air leak? I am trying to get some clue to where start. I maybe replace all other 3 oxygen sensors. or at least the upstream b1 sensor.

Has anyone had this problem before?

Thank you