I bought a 05 F150 with a bad motor, Truck looks great with no rust,a must have in Wisconsin. Just a blown motor, no problem!!!!! Ill have it rebuilt. Holy COW was that expensive. Ended up having to buy new heads,must be lined with gold. This is how I learned about VCT sensors and cam phasers, they are new too. They are picky. Found out that running the 5-20 oil don't work to well when the motor heats up. This is the USA standard or recommended oil for this motor from FORD. Motor wants to diesel in really slow traffic,cam phaser on passenger side of motor wants to act up. Found out that the oil flow Ends at that part of the head from the oil pump,oil pressure is low when it gets to that cam phaser. Have to rev motor to reset it. Found out that if I run 10-30 (just like they do in Europe for the same truck) it stops that. The 10-30 is what FORD recommends over in Europe,for the same truck I have here. It stopped the rattle in slow drive thru traffic. I don't trust the gauge in the truck dash,it reads a little above half way mark. I hooked a real oil pressure gauge up and realized that at idle warm it was going down to 9lbs. Under the recommended lowest oil pressure of 14lbs at hot idle. What I did do was put a spacer under the relief spring on the oil pump,this raised the hot idle oil pressure to 35lbs, 75 to 80lbs cold start up pressure. I haven't had that dieseling problem happen since I did these 2 things. Seems like I'm not the only one with this problem from what I read on this site,this helped me. Since I bascially have a new motor and the phaser problem fixed. The tranny took a dump,had it rebuilt and 2 weeks later the wrench light came on with the engine light. Low throttle,poor gas milage,shifting horrible and a slight miss in the motor. Ran a scan and every code on my truck came up plus blowing fuses. Tranny codes,o2 sensor codes,throttle actuator code,evap code TPS code and more. Took it to Ford to find out what the hell. They said wiring harness is junk and wiring harness is burned up behind plenum. A couple grand to fix it. Took it back to the tranny place and asked for help, and asked them if maybe a wire got pinched by putting the tranny back in. They have a camera that can look in tight spaces and they said they would look. They found the short and fixed it for free, it was a bare wire from the o2 sensor harness rubbing on the head.Thank goodness,by the way it was looking that wrench light should be a money symbol. Now my problem is a vibration at 35mph to 60mph. New tires and balanced and $700 for the rear end being rebuilt. Not rough but slight vibration,new u joints front and rear, maybe drive shaft ? I had to pull all the lights out of the truck that turn on when you open the door. They either stay on then go off after way too long then come back on again just sitting there, and turning on when I'm driving. Just a little history of my truck that I do like from a guy who only drove Chevy's my whole life.

 

I am having similar issues with oil pressure at low RPM's. Quick info on truck. 2005 lariat 4x4 180,000 miles
Items recently replaced:
Phasers, chains, guides, transmission, vvt solenoids, cam phaser sensors, plugs, alternator, battery, and transmission. I am wondering about the oil pump spacer you installed. Do you by chance have any pictures or further description? Did you use a new oil pump on the rebuilt engine or original? I am really at a loss at this point and am feeling dealership bound, unfortunately.

 

I used the old oil pump because it is still good. Just a washer as a spacer on the bottom of the spring. You have to pull the oil pan then unscrew the cap on the bottom of the oil pump where the spring is. Put it in and put everything back together. If you have a real oil pressure gauge,note your oil pressure before you do this and you will notice more oil pressure. In the winter I go back to 5-20 because it gets cold. But as soon as it starts to warm up out side I will go to the thicker oil. I also use Lucas.