when you say the tac ides erraticlly, do you mean the motor or just the tac is bouncing?
for you sputtering try this:
http://www.cb7tuner.com/vbb/showthread.php?t=30229

or this
http://www.cb7tuner.com/vbb/showthread.php?t=49352

also, check the ignition timming. later.