Ok so I'm posting this for my friends truck. It's a 01 f150 lariat with a 5.4. He replaced his intake manifold with a new one, and while in the process he replaced his spark plugs. After re connecting everything the truck had a shake to it on startup. It almost sounded like a misfire but we couldn't get the CEL to come on. With a scan tool I can comand the iac to go up and down as well as the egr. I checked the maf to make sure it was clean and it looked good. Next I tested the resistance of all of the cop and all of the injectors and still nothing. I found out that he had installed autolite plugs so we switched all of those out for motor craft and this made it a little better but it still has a bad shake and a rough idle. Finally made the CEL come on. The code was lean on bank 1. I sprayed carb and choke cleaner around the intake to double check for leaks and no change. I'm completely stuck on what to eliminate next without throwing parts at it. If anyone has something else to try that would be awsome!

 

spray soapy water around the injectors maybe a o ring is bad and letting air in too. And check the PCV valve and the hoses they tend to cause vacuum leaks.

 

I did check the pcv, no leaks or cracks the new intake came with a new elbow that you push in and turn. I also checked all of the o-rings on the injectors for cracks or tears when I tested the resistance and they all seemed fine but I can try the soapy water out tomorrow and see if maybe that shows anything