I would suggest the Injector 3 open circuit is the most likely cause. You have failed an injector (or a bad connection). I would clear it and then retest to see if it comes back. If it comes back instantly then the wiring/injector is at fault.
Open circuit suggests that there is nothing coming back from the injector i.e. its not connected or failed internally. Check the connection to it aswell? You may have a dodgy feedback pin.
The throttle error suggests you are limited and will not get to 100% (or 99% for that matter). By limiting the throttle you obviously will be hugely down on power and the engine is essentially being choked from the amount of air it can breathe.
You may find that the open circuit injector fault is causing the limp home condition on the throttle (seems likely, as the controller will not be able to measure how much fuel its trying to put into cylinder 3 and protects the engine from further damage by limiting the air it can consume).
You may also find that the O2 errors are also cause and effect of the injector malfunction (mis-fuelling will cause misfire which will affect combustion hence exhaust gases). The O2 is probably struggling to hold lambda due to the above and hence flagging the DTC (the rear CMS sensor may then think the CAT is not cleaning the gases as it should). Remember a CAT needs to remain at stoichiometric (lambda = 1) in order to successfully convert HC, CO and NOx tailpipe emissions).
Hope this helps.
Rez
