1987 Toyota pickup: Spark Plug Keeps Fouling

Hello ETCG Forum Members!

This is my first post here I am trying to see what direction I should go with this.

I have been doing some needed up keep/ mini-restoration on my 1987 Toyota Pickup 2wd 22R 2.4L 4 cylinder.

Today I am finishing up an almost complete brake system overhaul on my truck (all original but somewhat mechanically neglected ) and decided to take a look at my spark plugs again. I found that the spark plug on cylinder # 3 has fouled up again with what looks like oil and smells like oil. These spark plugs were changed out about 3,000 miles ago as I discovered the #3 spark plug’s outer electrode was in very sad shape (Last pic, OEM NGK Plugs). I will post pictures below. The first four pictures are the plugs that I just removed (OEM DENSO Plugs).

Here is a little back story:

The truck has been in the family since new. This truck was driven by my great grandmother and only has 75,000 original miles and is my first and only vehicle. The oil has been changed every 3000-4000 miles.

The truck did overheat about 5 years ago when my dad owned the truck and blew a head gasket (Somewhat common with the 22R engine). The head gasket was replaced at a local shop and the head was pressure tested at the time. The head checked out fine.

The truck burns about 1.5-2 quarts of oil every 3000 miles now where it didn’t used to burn any 3 years ago. I occasionally see blue smoke on startup.

Even though this may not help, dry compression is right around 175 psi for all cylinders.

Now to my question: In your experience, what is the most likely cause for the oil burning and the fouled plug? I know I will not get a definite answer until I tear it part but I am looking for a direction to go.

Thanks for any input!

-Jake