I have a 03 GT. 4.6 2v. It has 76k on it and it ran great till i did a small build on it this past winter. I put on a trick flow upper and lower intake and adjustable timing gears set at zero and comp cams stage 2. These part were on the car at one time but the previous owner had taken them off. I powder coated all the parts and built the motor. I used all the parts it had but installed the cams and intake. I set the dot (index mark) at 6pm, straight down and folded the chains in have not once but prolly 15 times and marked the ends. Im very ocd and do things a zillion times to avoid these issues. I out the top dot to the top and put the other mark on the opossing link that was marked. I triple checked torques, checked 100 times the intake and everthing before assembl. Zero vacume lecks. it runs great but has a hard knock!! It sounds as if its coming from the center of the intake. Its very rythmic to the motor but the motor seems to run greatr and idle as it would with cams. i have a fuel pressure gauge and it reads about 38. I have absolutly no vacume leaks. I checked and repalced the plugs many times. I did a compression test and the right side was about 180 or 179 and the passanger side was 168-175psi. I checked all fuses and harrnesses, have clean fuel, new oil filter and oil. I rotated the motor like 42 times after installing timining chains ti have all the marks line up again and to listen for anything hitting. Everything looked good. Nothing in the valve train either. When I raise the rpms the knocking speeds up. It sounds like a rod knock on a old push rod motor or like after u change your oil and you first start it up and it knocks, well thats how it seems to sound so I completely lost!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!