2004 jeep liberty 3,7 code p0135 changed o2 sensor check engine light comes on

SOURCE: P0155 & P0135

O2 sensors are tricky. sometimes like anything else they fail. many times though the exhaust mixture they encounter is out of their range and that shows up as a failure.since you seem to have no other problems , I would go ahead and change them, but don't be disappointed if the code shows up again (at least you know it's not the sensors.) I don't like using the process of elimination when doing repairs but sometimes you must.

SOURCE: 2004 jeep liberty thermostat change?

ihave to change my thermostat in my 04 jeep liberty is it hard

SOURCE: check engine light came on and the code came up as

http://www.obd-codes.com/p0441

click the link for details on code P0441

SOURCE: 2002 Jeep Liberty P0174 code and mech has changed the o2 sensor

Can't tell you exactly what is wrong but the one thing you said is of concern...Map sensor should not be full of oil. If it is, I'd want to know why. In finding the reason for that, you may also find the reason why you are having a problem.
Jeep uses two kinds of engine crank venting. you either have a pcv valve or an orifice controlled system. If either are obstructed it can overpressure the crankcase and cause all kinds of problems.
Years of experience tells me this isn't something I can guess at and be 100% sure I have the right answer but based on what you said, I'd look there first!

SOURCE: i've changed all of the

The wiring harnesses for the O2 sensors run right next to the exhaust manifold, and get incredibly hot, sometimes causing the wires within the harness to crack or break. This would cause your problems. Have a look at the harness and let me know what you find.