I have a 01 saleen sc that has a issue running rich, its not trowing a cel but is stumbling in normal driving at around 2500-3000 rpms . have recntly changed plugs (ngk tr6) and cops( motorcraft) same as it had before . Put my scanner on it to night and found the fuel pressure at idle was 38-40 psi and if u revved it to about 3000 it jumped to 51 psi, also the short trim was reading negative 20. unplugged vac line off fuel reg and it jumped up a few psi . Any thoughts or ideas, also removed...

2001 saleen runnig rich