thanks for the link I will check it out on saturday. I have to work all next week. YUK

Do you think that maybe the throttle body could be the bad guy here??

When you replaced the sensors, what year did you use? If you based it on the 96 LSS body, but not the 99 PCM, that could be the problem. Sensor part #'* change throughout all the years.

he said he had the issue before all that, i would bet on a vacuum line check those common ones i mentioned

Yea this problem has been in the car before motor swap tranny, ecm swap etc.
The vacuum hoses are new all of them including boots

maybe iac seat in the tb base then, or carbon build up on the butterfly

Oh my bad. I missed that part about it doing it before the swap.

Have you inspected the EGR pipe? A leak could cause the lean condition. I know it'* weird that it would be only on one bank. But, Boosty has seen it before.

i'll recheck the egr pipe.

When my motor final quit working, I got real lucky and found a wrecked 07 buick Lucerne with less then 6k miles in a local junk yard. They sold me the engine with everything on it except the belt system. I paid 600.00 for it. So when I installed the motor I used about 90% of the parts from the lucerne. I had reused my metal upper intake, my matched flow injectors, fuel rail and regulator, also my throttle body with sensors. I had to use my rear exhaust manifold, but that'* it the rest is from the 07. I/ll go grab a used throttle body today and try it out this weekend. I'll let you all know. And thank u for all the help.

ok I have found a bad o-ring for the iac. Still the same problem. I just ordered a fsm. I'll let you all know