I discovered this morning that the SeaFoam didn't help as much as I thought it did....Still sputtering, backfiring, surging, and stalling.

One thing I did for the temporary is I pulled the small vacume hose loose that runs from the air cleaner compartment to the intake vacume tap. With this loose I found the idle is smooth as silk but running about 1300 RPM's in Drive, and almost 1800 in Park or Neutral. A little sputtering but no backfiring, stalling, or surging, although there is a very noticable decrease in power. Being a 2.9, how can I idle this down? I know the vacume hose being removed is a bad idea but had to do something to get home. Could this possibly be a sign as to what is wrong?? Any ideas???