With hydraulic lifters there is usually no adjustment but 2.9l does have this.
What you are doing in this adjustment is compressing the hydraulic lifter for each valve the same amount, so the 1.5 turns is very important it needs to be exactly the same for each valve.
Adjusting valves with engine off is best, IMO, but you can do it with engine running.
Look at running engine to see what direction the crank turns, use that direction in the following.
Engine cold
Remove spark plugs, valve covers, lift distributor cap
Rotate crank to TDC and look at distributor rotor, if it is pointed at #1 spark plug wire then you are at #1 TDC, if it is pointed at #5 wire then rotate crank 1 full turn to TDC again, rotor should be at #1 wire now.
You want the cam lobes to be at the lowest spot when you adjust the valves for a cylinder, that is the start of the power stroke, the intake valve has been closed for 1 full stroke(compression) and the exhaust valve won't open for another full stroke(power).
On #1's valves loosen until rocker can move, there is lash, tighten just until no lash, then tighten 1.5 turns more, some prefer 1.75 turns, you can do either but it must be the same for each valve.
Firing order for the 2.9l is 1-4-2-5-3-6
Rotate crank until rotor is pointed at #4, about a 3rd of a turn
Repeat valve adjustment for #4's valves
Rotate crank another 3rd turn so rotor is pointed at #2
Repeat valve adjustment for #2 's valves
Rotate crank another 3rd, should be back to TDC mark, use it, rotor is pointed at #5
You get the idea
Repeat all until #6 is done
Yes, you can match one cylinders intake valve opening with other cylinders being at TDC power stroke, same as above is matching distributor direction to cylinders stroke.
The intake valve method would be used if distributor was removed and hadn't been put back and timed.
Since your engine is obviously running I would use the distributor.
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