What is the ibs on a ford windstar 2003 rocker arms to adjust the lifters

They are hydraulic lifters. Remove rocker covers, start motor, they will rattle oil, tools are available for that. Loosen rocker nut until you here tapping. Tighten nut until tapping stops. Then tighten 3/4 of a turn. It will run rough for a minute until the lifter adjusts.

In engines with rocker arm valve systems, the procedure I'm familiar with is to remove a rocker arm cover, and (one at a time!) while the engine is running, slowly back off the rocker arm retainer nut or bolt just until you hear the lifter tapping, then tighten it a quarter turn. If you can identify a lifter that is already tapping, tighten its rocker arm slowly until it stops tapping, then adjust it. Do not over-tighten! This can damage the engine.

Listen carefully to how the engine sounds; if it starts to stumble when you tighten a loose rocker arm, you've gone too far. If you cannot get the engine to run well without tapping, you may have too much wear in the valve train and may be due for a head overhaul, or you don't have adequate oil pressure in the lifters in question.
Repeat until all rocker arms are done. Replace the rocker arm cover using a new gasket, then (in a V-engine), repeat the procedure on the other side of the engine.

Wearing safety goggles, or better yet, a transparent face shield, is strongly recommended. Sometimes oil will squirt out a considerable distance from the lifter side of the rocker arm during adjustment, and the direction is not readily predictable.

If you have hydraulic lifters(tappets) then you turn the adjusting screw 1/4 turn past the point where there is no noise from the rocker arm. If you have solid lifters, then you'll have to get the cold clearance spec for that engine and adjust accordingly.

Valve Adjustment

Print
The 4.2L and 5.3L engines do not require a periodic valve lash adjustment.
The 4.3L engines are equipped with screw-in rocker arm studs with positive stop shoulders. Because the shoulders that allow the rocker arms to be tightened into proper position, no adjustments are necessary or possible. If a valvetrain problem is suspected, check that the rocker arm nuts are tightened to 18 ft. lbs. (24 Nm). When valve lash falls out of specification (valve tap is heard), replace the rocker arm, pushrod and hydraulic lifter on the offending cylinder.

If this all happened after pan gasket change, chances are you knocked the oil pump pickup and the pump is sucking air. You've lost oil pressure. Fix that. Do NOT add washers. That's not your problem.

There is no adjustment on the rocker arms. The lifters are hydraulic.
So if you are hearing lifter noise, chances are it is lack of oil or oil pressure.

If your rocker arms are adjustable you can adjust that rocker arm by tighten it up a little at a time until tapping stops but,if the rocker arms are not adjustable or have a net lash then you will need to replace the lifter.

If it's a "K" code hi-po 289, then it has solid lifters and the valve clearance is adjustable. If a standard 289, then it has hydraulic lifters which are zero clearance and self adjusting, i.e. there is no adjusting screw on the rocker arm.

this car uses hydraulic lifters. If your lifter is tapping, make sure the nut is tight on the rocker arm. If it still taps, the lifter has failed and must be replaced.

no adj there,
if you have ticking noise from lifters replace them