I have a 89 ford ranger with a 2.9 v 6 and the lifters are tapping it has good oil pressure .

You should have a Chilton's book or the shop manual for the truck

A lifter problem can only be fixed by changing the lifter. You might as well change all of them because it is just as easy since you have already had to take the heads off to get at the noisy lifter. While you are at it, get the heads reconditioned or a valve job. More than likely the oil was not changed as often as it should have been. Dirty oil works like sand paper on the valve stems.

most likely a lifter, usually caused from low oil and infrequent oil changes

Could be low oil level, a bad sending unit, or actually low oil pressure due to a worn oil pump or worn bearings.

Usally it's a stuck or colasped lifter. You can check your local parts store for oil additives that may unstick the lifters, often you'll have to replace the lifters. Also check oil level and oil pressure.

crook lifters and or dirty oil

the lifter noise might have been a bearing going bad or a piston ring. if you lost power you probably lost compression on one cylinder. Try checking your compression with a compression tester screwed into your spark plug socket. here is a site with a procedure.
http://www.automedia.com/Engine_Compression_Test/ccr20050801cc/1

You may have something in the oil pan clogging the sump screen. When the oil pump turns and picks up oil it feeds through a pick up tube that runs at or near the lowest point in the oil pan. This low point is where trash usually accumulates. Trash meaning pieces of old gaskets maybe from an older repair. When the oil is picked up through the tube it must pass through a screen. As the oil is picked up the debris is also, resulting in a engine that is starving for oil. The lack of oil pressure causes the lifters to go flat and thus the tapping or clicking occurs as a result. You need to correct this situation because the lack of oil pressure will or may damage the engine. Good luck and let me know the final outcome. Myself or someone else will be glad to offer more assistance.

if its an ohv type the most common fault is that the oil ways to the rocker shafts become blocked
so get some flushing oil drain the oil and replace with the flushing oil and run for the time stayed on the can then Change to good quality oil and new filter
then remove the rocker covers and check and adjust the valve clearances
if its an ohc type its all hydraulic adjustment
you could try flushing as above but apart from that the only other way is to change the lifters and followers
hope this helps

Possibly clearances "closing" at operating temparature? 20w50? Kinda heavy isn't it?Spun bearing - should make more noise than a "Tap"? I've heard several low and high mileage 2.9 engines "tap" but quits after warm up? That SEEMS to be somewhat common with the2.9 Sorry can't be more specific.