Maybe I missed it , but have you sniffed the dip stick to see if you have a little bit of diesel
getting into your sump? Major dilution would cause problems very quickly, but small amounts of diesel
in the sump might be just enough to give your symptoms. Have you done an oil change
during the time that this problem started? I actually agree that your pressures are just fine, but if they have changed recently, it is good to investigate. Best of luck. ______Grant.