[tmoss]

If the diaphragm in the fuel pressure regulator fails, it won't control fuel pressure correctly and the leaking fuel gets sucked into the upper intake by the vaccum line = WAY too rich.

Look ast my sig, 277rwhp on 19# injectors and I have nothing more than an adjustable fuel pressure regulator and the base timing as tuning tools. A "large comp cam" and definately the 24# injectors are playing havoc with the computer VE tables. Do you have the 19# injectors you could put back in? If a MAP check, computer change and trying the 19#ers result in no change, I'd definately go to MAF and forget fooling around with a chip for the SD system - it will be cheaper and work better.