This is right, If you look at lines in the mid 400's pressure across the injectors drop, the fuel trim on both banks drop, and the rail pressure drops. It pretty consistently dropped the more the RPM's went up though which is fine and just shows that you are reaching the top of that pump. They didn't leave much room for the early cobras and mach 1 guys as far as fuel goes. They use the same pump as the GT's with the terminator being the exception of course.
Yeah, you can see evidence of it in my AF chart as well. I'm comparing (overlaying in Photoshop) other dyno sheets from Mach's with the same cobra cams swapped in, and they are pretty much identical as mine up until around 4.5k, where mine takes a slight dip, then after 5k where my curve levels off and they all continue to climb up to around 320-325. I may run her on the dyno again after the pump replacement, hoping to get closer to the 320s.
As I recall, you've had a pretty much uphill battle with this car from the get-go. Happy for you that those days seem to be coming to an end finally.
Nearly, so far I've had to replace the engine, half the dash light bulbs, the rear upper control arms, re-weld and reinforce the rear upper torque boxes (one was completely off the car), have a crack in the chassis between said torque boxes welded, replace a brake line, fuel tank grommet, the front ball joints, and the steering rack. I'm really just trying to her into top shape to sell off at this point, so I can get a properly (or actually) maintained GT or maybe find a Mach 1 that needs some love.
2007 Mustang GT - 5-Speed, Airaid CAI, 4.10s
2001 Mustang GT "Mock 1" - 5-Speed, 03 Mach 1 Swap, 98 Cobra Intake Cam Swap, BBK CAI & Longtube Headers w/ H-Pipe, 4.10s 302 rwhp / 310 ft-lbs
2015 Ford Fiesta - Wifes
1981-82 Mustang Cobra/GT T-Top
1984 Mustang GT T-Top - Bare Chassis
1984 Mustang GT350 - 302 / 5-Speed
1984 Mustang LX - 302 / 5-Speed