codes - random misfire and cylinder banks 1, 2, 3, reads out lean fuel
will be checking out injectors and rail pressure, however, need any suggestions on trouble shooting in general for this issue.

 

Look for vacuum leaks and or bad intake manifold gaskets.

 

wtroger - as suggested, will check out vac leaks and/or bad intake manifold gaskets. thanks much for your speedy reply!

 

Have checked for vacuum leaks and bad intake manifold gasket and found no leaks, any other suggestions would be greatly appreciated.

 

...at the same time, could it be the oxygen sensor on that side causing the lean fuel read out?

 

May be a upstream O2 sensor problem, as all the cyls are on the passenger side cyl bank-1 & if the O2 sensor for that bank is acting out & sending the computer corrupt PID feedback about true exhaust O2 content, it could cause the computer to mis-control injector squirt time.
So do you also have a trouble code for that cyl bank O2 sensor????
Have you tested its switching range & speed???
If the O2 sensors have more than 75K miles on them, they belong on your trouble shoot suspect list.
Post All trouble code Numbers you have, as they can offer up good trouble shooting clues.

 

pawpaw

After trouble shooting your excellent recommendations and replacing the MAF and O2 sensor in question resolved the problem.

Thank you very much!

 

OK good trouble shooting find, fix, feedback & to hear all now seems well & your on the road again.
If you didn't also replace the drivers side upstream O2 sensor, seriously consider doing so, to keep the fuel trim range & speed in balance between both cyl banks.
I replaced both upstream O2 sensors on my 94 Taurus 3.8L a few years ago, after one began giving me a random CEL with a lazy switching/response trouble code.
As they age their switching speed, range & response time slows, sorta like me!!!! lol
So to keep the computer happy its customary for us to replace Both cyl banks upstream/before cat converter O2 sensors at the same time, to help it keep both cyl banks fuel trim in proper balance.