I've been fighting a doggy PSD since I had the dealership put in a new PCM in. Shortly after that I installed a K&N filter bought on Ebay. (Worst investment yet). Needless to say, the truck wouldn't pull a 7K load of hay over 55 MPH. I took the time this past weekend and checked the fuel pressure, 65 PSI at idle. Since I had the parts, I installed a new regulator spring and o-ring, replaced a faulty fuel bowl heater and installed my 6637. Holy crap... Chasing a little F150 with a 1500 Lb load through the hills and myself hauling the usual 7K load I thought I was going to run him over..I'm still not blowing black smoke like it did before the dealership screwed with it, but at least I can pull again
Thanks to all, you guys are the best !!!!!

 

Thats good you can see a difference. Wait till you get the exhaust and DP-TUNER, thats when you will have a new truck.

 

I've got a bit of work before then.. I have an oil leak and/or blowby issue to the tune of 1 Qt/200 miles first (gonna pull turbo soon). and still have low boost issues (max 12 PSI). This was a salvage yard rescue truck and had been abused before I got it. At least I have straight sheet metal now, different colors yes, but straight..
What kills me is that before I had the dealership mess with it, I was getting 16 MPG running on 6 cylinders !!!!

 

Ok, I understand what you are going through. You know what to do if you have any questions.

Good luck.