The Nissan Path

I've got at 01 Pathfinder manual transmission with 220k miles on it. I've owned it since new.

Recently, when in low speed and high gear, it's riding rough and it has gotten worse.

When I checked the codes at Auto Zone, P1140, P1145 & P1320.

They seem to think something is wrong with the timing and to not use it until a mechanic takes a look at it.

Mechanic thinks it's the timing chain.

Is there anything I should be changing first before the timing chain?

Check the oil pressure. If the oil pressure is too low, there are oil gallery cover gaskets on the rear timing cover that can fail and cause low oil pressure. It's getting to be a fairly well known issue lately on the VQ engines. Also, dirty oil or low oil can cause this, as well. I wouldn't expect the 1320 code to be related to this, however, That is usually an ignition coil failure. The question is which one without a specific cylinder misfire code to go with it?