Chrysler Repair: fault codes P0300,0153, chrysler sebring convertible, thoughtful observation

Question
P0153 and P0300 oxygen sensor and #3cyl misfire this is what my report from chrysler dealership stated. they did not fix or offer any sugestions.  chrysler sebring convertible 2.4 v6 2008 yr model

Answer
Hi Don,
You didn't mention the history of this situation so I can't be too insightful. The 0153 is reporting that the upstream oxygen that is mounted on the exhaust manifold of your engine is not responding as it should (slow response) but I wouldn't expect that to cause a misfire, but rather a loss of fuel economy or increase of pollution from the tailpipe. Replacing that sensor after verifying that the harness wires to its plug are not the problem, is the likely solution.  
The 0300 is a multiple cylinder misfire, whereas a #3 cyl misfire code would be 0303. The problem with the 0300 is that the list of possible causes is very long and so requires some thoughtful observation and possibly diagnostic scanning of the engine operational parameters to try an eliminate unnecessary investigation of parts of the system that are probably OK. I can give you that list, for whatever help it may be to you.
If indeed it is just cylinder #3 then that helps focus on either the mechanical aspects of that cylinder's function (like measure the compression of the cylinder to be sure the mechanical aspects are ok), the spark plug/wire/coil aspect of that cylinder, or the fuel injector function of that cylinder. So if you would clarify whether it is 0300 or 0303 that would be helpful.
But even more would be to know if you are equipped/interested in trouble-shooting this yourself or are you just trying to decide who/what to authorize to work on correcting these codes. And again, I don't know the history or the actual driveability that led you to the dealer for a code readout. So I will leave it at that and await further information.
Roland