Leaky injector?

[imported_Sleeper]

@01GPGT

bad vac line could cause it but you should set a check engine light first. unmetered air entering is going to be compensated by the pcm adding fuel, when the fuel trim stategy reaches it’s limit it’s going to set a lean code.

if you can scan check your long term fuel trim at idle, if it’s high positive it’s possible you have a leak

have you changed out the PCV? atleast spray it out with some carb cleaner

bad vac line will not set off a code on the 4.0’s, these motors are more forgiving than anything i have ever worked on before SES wise. Havenet scanned for LTFT yet but i have see bit and didnt look out of the norm…