Is it a stock Mustang 4.6, 2V MAF?
Stock injectors (should be orange)?
What is the fuel pressure, should be 28 psi or so, at the rail at idle?
What sort of fuel system are you running, has the tune been set to run with whatever fuel supply you are running?
- 2003 GT, UPR X, FRPP 24lb/h, Magnaflow, PP 70mm TB & plenum,
Delta Force tuned, Steeda UDPs, Ralco flywheel,
RAM HDX clutch, 3.73s, 262 rwHP/305 lb-ft.
New ride (7/1/2013) 1998 Mercedes SL500-5.0L 32V VVT 326/347 HP/tq
Engineering is, at its base, making what you want from what you have.
At its extreme it is making what you want from what you can get.