Yes get a wideband and an EGT gauge. If you have that setup, you should get some larger injectors. Stock ones simply cant handle crap.

Then, call Vortec and get the calbration kit for the SFMU. In the calbration kit you will find a vacuum resistor. Put the vacuum resistor in line between your vacuum source and the SFMU. That should clear up your small lean condition. Install the resistor with the larger end toward the SFMU.