Greetings!
In our shop we have seen many of the 5.2 engines used in Dodge trucks with oil pump failures in teh last several years, giving symptoms just like you describe. Often, upon disassembly large sludge accumulations are found in the oil pan even on vehicles where the owners have performed routine oil changes. Some of the time there were no other symptoms (such as valve train noise), because oil pressure did not drop completely to zero.
Since oil starvation can result in major engine damage if left uncorrected, it would be a good idea to have this problem diagnosed and corrected ASAP.
I would recommend having the oil pressure measured directly at the engine with a mechanical gauge to see if it is a sender problem or an actual oil pressure loss; usually it is an actual pressure problem on these engines. I have performed TSB searches several times but have nevver come across anything from chrysler acknowledgeing any problem with these oil pumps, but in our experience failures are very common. Also, always install a new pickup screen when replacing the pump.
I hope this is helpful; if so, an accept would be most aprpeciated! thanks!
