when you say the right bank is lean and the left bank is rich, what are the numbers? what are the fuel trims, long term and short term?
can your scanner look at the activity of the O2 sensors? Are all the pre-cat O2 sensors
cycling back and forth below .2 and over .8 volt?
since you have a snap on scanner to use, did you do the minimum idle test using the scanner?
what was your fuel pressure spec?