Looking for torque setting for 2002 ford ranger with a 3l rocker arms

I have a sneaking suspicion the 18 lb is the torque to set the rocker studs in the head. As for setting the hydraulic lifter preload there are a few conflicting opinions but check out the link below...

https://advrider.com/f/threads/gm-4-3l-valve-adj-procedure.848987/

No torque sequence on rocker arm bolts. 11 ft lbs plus 30 degrees.
A torque wrench rated for inch lbs should be a finer adjustment.

There isn't any. Just torque specs. Tapping could be lifters, push rods worn, rocker arms worn, or the cam is worn.

There is no adjustment , install rocker arms an torque to 18-28 lb/ft

The torque settings for the cylinder head on a 2003 Ford Ranger 2.5 turbo diesel WLT engine are as follows:

• Main cap bolts: 70 Nm (52 ft-lbs)
• Head bolts: 65 Nm (48 ft-lbs)
• Rocker arm shaft nuts: 25 Nm (18 ft-lbs)

It is important to note that these torque values are for the cylinder head bolts and main cap bolts only. Other fasteners on the engine, such as the oil pan bolts, may have different torque requirements.
It is also important to use a torque wrench and follow the proper tightening sequence when installing the cylinder head. Consult the service manual for your vehicle or a repair manual for the specific tightening sequence and additional torque specifications.
I hope this information is helpful. If you have any further questions or need additional assistance, don't hesitate to ask.

If all parts on this motor are stock and it is not a high performance engine but a stock windsor unit, there is no actual torque standard for the rocker arm nuts since the lifters are hydraulic. The manual procedure recommends the following:
with the motor off, tighten all rocker nuts until there is no slack between the rocker arm and the tip of the valve stem. Make sure each rocker is on the heel of the cam, this proceedure can be done one cylinder at a time or you can follow the ford V-8 cylinder identification for valve clearence sequence. I like the one cylinder at a time, it's a little slower but I think it's more accurate. after all rockers are set to the above mentioned clearance, start the motor and let the oil pressure build up in the lifters. At this point you should have installed the oil deflector clips on the rockers, just above the oil squirt holes, otherwise, things get a little messy. when the oil pressure is up, tighten down on each rocker until the engine starts to miss. At this point back off enough to clear the engine idle up and move on to the next rocker. Hope this helps.

This might sound weird but how about an exhaust leak at the manifold?

Stuck Valve.Or just about ready to stick.