Welcome to TRS
Smell the white smoke, if possible, coolant passing thru the engine(head gasket issue) has a distinct smell, sweet, like burning coolant, lol.
Are you losing coolant?
Do you have to "top it up"?
Overheating or Coolant in the oil are last stages of a blown head gasket so you don't have to have that, to still have that problem.
Cracked head acts the same as blown head gasket except you would never get coolant in the oil.
1987 2.9l did have that issue with the heads, I think it was fixed in the '88 or '89 model year.
Anyway there is a simple and free test to see if head gasket or cracked head is the problem.
The Glove test
Cold engine
Remove rad cap
Remove overflow hose from rad
Remove Coil wire from distributor cap or coil, you want a no start
Plug overflow hose port on rad, gum, vacuum cap, hose with bolt in the end, ect.....
Put a Latex glove over rad cap opening, and seal it with a rubber band, you can also use a balloon or even a condom in place of the glove.
Now crank the engine and watch the glove
If it just lays there then all is well
If it starts to bounce then you do have a cylinder leak, i.e. blown head gasket or cracked head.
If it bounces remove 1 spark plug at a time and crank engine, when it stops bouncing the last spark plug removed was from the leaking cylinder.
reinstall that spark plug to confirm.
Knowing what cylinder is leaking does not help fix anything but it can help you ID a cracked head or blown gasket when you get things apart.
If you pass the glove test and are losing coolant then could be lower intake manifold gasket is leaking coolant into a cylinder intake runner, via the coolant crossover passage, very rare occurrence, but can happen.
On 2.9l that would be either cylinder #1 or #6 I think, #3 and #4 would be possible but an even longer shot that #1 and #6.
You can check #1 and #6 spark plugs, pull #2 as well for a "this is what it should look like" plug
If either looks "steam cleaned", very white porcelain then it is being steam cleaned, by leaking coolant.
IF(big if), you passed the Glove test then best bet would be to plan on changing the upper and lower intake gasket.