This problem has boggled me. My 540 will hesitate briefly, with popping (in intake perhaps), upon initial acceleration (1-2k rpm).

I can't seem to duplicate the problem while it is in neutral.

Something also worth mentioning is when I first start the car, if I put it in reverse or drive (put load on engine) fairly quickly the idle may bog down and the engine may die completely.

Fuel pressure is around 40PSI. I'm going to test it with another pump because I think it should be a tad higher (possible variable error in gauge though).

MAF is clean.

I DO have some nice exhaust leaks before the 02 sensors.

Any ideas?