The new 4.0 is in and started up easily. But it develops a miss at 3,000 rpm where do I start looking for the issue? And there is a po174 trouble code (bank 2 lean) I'm going to clean the mass air sensor and check for vacuum leaks. Anything else?

 

A wallop of fuel injector cleaner?

 

Sorry brand new injectors

 

Assuming 1995 or up 4.0l since its OBD2?

What year, and manual or automatic transmission?

Did you wire coil pack correctly?
3 4
2 6
1 5
front

The 5 6 4 side has got me more than a few times, trace each wire to its cylinder


The engine computer has a REV limiter set for 3,000rpms
If computer thinks transmission is in Neutral then it will start to cut injectors off above 3,000rpms
Manual and automatic use different "neutral sensors"

Lean code can come from a misfire, and not be the cause of the misfire, bank 2 is drivers side of a Ford V6 so if misfire is in cylinders 4, 5, or 6 then that could cause the Lean code on that bank, another reason to check coil pack wiring