first tune up at 155,000 miles

I bought a very nice 1998 XJ Sport 4.0L with 155,000 miles for cheap with no apperent mechanical issues. All the fluids were changed regularly including coolant, but the vehicle never had a tune up. I've replaced the plugs (couldn't beleive the engine ran as good as it did after looking at the contacts on the original plugs). Later this week I will replace the plug wires, distributor cap and rotor. Is there anything else I should replace as a precautionary measure (belts, O2 sensors, u-joints, etc...)

Fuel filter, air filter. Grease U-joints.

Change the serp belt if it hasn't been already. Might be time to do the timing chain also.

what is the service life for the timing chain on the 4.0L? That is one thign you never see or hear about changing on this site, except when doing stroker or rebuilds.

X2 on the timing chain. I tried looking it up in the FAQ but I didn't get anywhere....

IDK about actual life of a timing chain...but my 4.0 has 219K on the clock, with no major shop time (no timing chain work). Course, that's an 89, lots of small stuff changed btwn 89 and 98