Our 2001 s-type engine light keeps coming on. Have put all new o2 sensors in since that what the scanner says. Its always bank 2 sensor one. I read some where that a leaky intake gasket,leaking exhaust, misfire,etc could be the cause. Does anyone know a good place to start. Thanks,Wdlittell

 

You pretty well defined the potential issues. Brake cleaner or even WD40 can be used to spray around the intake manifold. The engine idle will change if the fluid finds a vacuum leak.

I'm fighting the same thing on another Ford car (P0430) at the moment. Comes and goes, no clearly identified issue. Changed o2 sensors. Leaks in the exhaust prior to the sensors have been identified as a potential problem but short of pulling everything apart not sure how to address that.

 

It would help if you could provide the codes you are getting.