That is why I was asking, now I have a better idea of what you are up against. Does the truck seem to run OK, any unusual noises or weird problems to indicate that you need to explore the heads at this time.
If I had the time, and if I was keeping the truck for awhile, I would probably pull the heads and inspect and at least have them checked for cracks and install new headgaskets assuming both the head and engine surfaces are not pitted.
That being said, if all you are going to need to deal with are the leaks, I would suggest the following:
Remove the complete intake
Cleanout the sludge and crap from the engine
Replace all the vaccum lines you can
Take the manifold apart and clean out everything, all the vac lines, the throttle body
Clean out the top of each head, the rocker area, with carb cleaner so it is bare clean again
Replace any and all hoses that are questionable
Put it back together, start and warm up then do both a coolant change and a engine oil flush and change.
It's a 99 so replave the old plug wires while it is apart, I would suggest 8mm blue Magencor wires.
Replace the spark plugs with Bosh Platiumn Plus 4's
Drive it for awhile, make sure all is fine anf then after you have recovered from thqat expense, replace the O2 sensors for at your mileage they are crap and cutting your power.
Then go to another 127,000 miles and enjoy the truck.
Good luck,
Mike J.
