haha, I've just seen stubling idle caused by mafs turbulence before, simply because there was no filter. I'd think that an intake manifold leak (sucking in air after the mafs) would make it run lean as hell. You might try the usual idle killing suspects, like IACV, coolant temp sensor, very retareded timing (off a tooth), maybe O2 sensor. Do you have the vacuum reference hooked up on the FPR?