So I used a small smoke machine to check the intake areas (Used the Brake Booster Line) and nothing showed up. I then used the machine to check the exhaust, I found a pretty good leak where the Y connects to the straight pipe (Looks like the clamp rusted off) However not sure this is a problem since it is after the cats and O2 sensors.
It may or may not be your problem,
But it definitely CAN be a problem. Especially that close to the cats and o2 sensors. There are plenty of conditions in a normally operating engine that can draw outside air in through an exhaust leak and effect the nearby oxygen sensors. Especially if it is a big leak.
For example, during engine braking. The throttle body blade is closed but the engine is spinning kinda fast, this will create high vacuum in the intake system, so during the portion of the otto cycle when the piston has just finished ascending the exhaust stroke, both the intake and exhaust valve are open at the same time (valve overlap), and the high intake manifold vacuum allows exhaust gas to be drawn back into the cylinder/intake. The sudden change from + to - pressure in the y pipe can draw outside air in through a leak, which will mix with exhaust and read lean.
Fix it then test drive.
Even if that doesn't solve your problem, you will have factored out a relevant variable. If you leave things broken all over your truck, they will add up to create problems.
If the problem still persists after fixing ALL exhaust leaks, swap coils and injectors to the other bank. Inspect the spark plugs and either swap banks, or replace them.
