p0140 and misfiring

hi, my 96 gt 2.4 has had alot of codes come up recently with the really bad misfiring. My newest code is p0140 bank 1 sensor 2, well I replaced both o2 sensors about 200 miles ago maybe one wasnt spliced good enough but is sensor 2 the after cat sensor? And I think the after cat sensors just tell you if you cat is working, well that is how it works on my mustang. So could this be a reason for the really bad misfiring? If replaced so far, fuel filter, 4th cylinder fuel injector (for code cylinder 4 misfire code) spark plugs, coil housing, egr and boots. After i replaced the injector for cylinder 4 i got the p0300 i believe it is or whatever random misfire code is. Car starts great and wont misfire if I go very very slowly, but if I give it more than a little gas it starts misfiring like crazy. Any ideas? 3 more injectors? fuel pressure regulator? thanks ahead of time guys

I would check the fuel pressure before doing anything else. It is possible for the pressure to be too low for the injectors to work properly. You replaced everything except the coils. I believe that the coil housing and coils are seperate on this engine. I would replace those next. If the coils were replaced then you may have an injector issue. If the You have new plugs and wires so the next item on the list would be the coils. Also make sure that the plug gap is correct. It can cause misfires if too little or too much.

thanks for the quick reply. what should the fuel pressure be at idle?