2001 Ford CV P430 code help please?

[baba]

Hello, i have a 2001 Crown Victoria, and i recently changed the engine because it broke after 430K. The new engine looked pretty good and it only had 120K. Once my mechanic installed the engine, did a tune up, and changed the oil. I should mentioned that the car was stopped for a week before i started driving it because i was on vacation. The first day that i drove the car everything felt good. That day i drove about 170K. Near the end of that trip i whenever i stopped at a red light, i felt the engine shook a little bit, it felt like misfiring. Then i got home and didnt drive it until an hour later, At which it continue to misfire whenever i was stopped in at a red light (the misfire was very subtle). Then while i was driving once i reached 60-70 Km/h the car was jerking a little bit (misfiring). Once i got home that night i used the computer on the car and got a code P430. When i drove to work the following day the car didnt show any signs of misfiring, can it be the coils or the new spark plugs?. Can somebody help me with this please?

[G O R T]

Misfires can cause a P430, this narrows it down to bank 2.

If the problem is now constant, you can run the KOER diagnostic including the cylinder balance test.

Swap COPs and recheck to see if one is responsible. Injectors at the end of the rails can also malfunction.