Car leans out on right bank

Simply this means the O2 sensor servicing the #1 bank is reading lean. (I could go into more details but don't want to complicate the issue)

One needs to check the O2 sensor response (test procedures can be found in many shop manuals or Haynes tech books) and verify the O2 sensor is good and giving accurate information.

Once you verify the information is accurate from the O2 sensor one must look for the cause of more air entering the combustion process then the ECM can trim out. Usually, the culprit is a vacuum leak of some sort downstream of the throttle body (vacuum hoses, leaking intake manifolds, fuel injector O-rings, etc). Unfortunately, there is no magic bullet - you are going to have to hunt for the leak and fix. One way to do this is to squirt oil or carb cleaner at the gaskets and suspected leak areas while the car is idling and listen for changes in the idle characteristics. a shop manual can provide additional details