Hi folks, I hope there is someone on here who has experienced this issue. I got a 2005 Mercury Grand Marquis that has a miss at idle but runs great on hard acceleration or cruising. I have done the following, New plugs, coils, injectors, intake manifold o2 sensors. cleaned MAF, and EGR valve. I have a miss at idle, I did a power balance test and the IDS shows -20 on cylinders 5,6,7,8 (drivers side bank). No DTCs. Long term trim 1 is +12 and Long term trim bank 2 is -10 I attached the screen shots.
I also unpluged the brake booster and had no effect on idle. I installed a new PCV valve as well. I swapped coils and injectors from side to side as well. the problem did not follow the components.

Idle in gear

Idle in gear

 

If the problem goes away when RPM is increased, the PCM gets notified more fuel is needed and the condition is gone.
SO,,,,,,,,,,,,,,I would look for a vacuum leak, Could be anywhere.

 

Thanks, Tomorrow if it is not raining, I will go ahead and plug the PCV, and all of the other vacuum ports on the engine with rubber caps and see if it changes anything. Today I sprayed all of the fittings with Either and it did nothing. If plugging off all of the ports, i will borrow a smoke machine from my work and smoke test the intake system.

This may sound stupid but does anyone think a cracked fly wheel could also cause this one bank to be low on power? I know I am grasping at straws at this point.

 

I noticed the rpm is really low 632 rpm and the spec is 790-815 and the map sensor is reading 5.21 PSI . Thoughts?