alternator feedback?

[slammd72]

my truck doesnt seem to stop running even after i turn the key into the off position and pull the key OUT! after the key is out it begins to idle slower, probably because the power is cut to from the battery? right?

the only way i can get it to quit is by putting my hand over the tbi or flipping the tank selector switch to the right tank. (the right tank is removed along with the tank selector valve)

ive replaced both relays on the top of the fire wall. and the battery is brand new.

could "alternator feedback" be the problem? i dont know what alternator feedback is, but i saw a relay kit in the latest summit that is supposed to fix this problem. as stated in the small description.

the specifics on the truck are:
1988 CrewCab Dually 454TBI all stock engine compartment