I figured it's about time I entered this thread. I'm no cooling system expert, but I played this same "ball game" with my jeep for the last 6 or so months. Rusty up there can vouch for that.
So judging by all the posts, and all the things you have tried to do, I have what I hope is an answer to your problem. So you have an IR thermo? Perfect. Run the engine till it gets pretty warm and start diagnosing. Measure as many different spots of the block as you can and note ANY hotspots. Measure the exhaust manifold tubes for each cylinder and see if one is hotter/cooler than the other. Also, are you still going through coolant?? Have you retested the block for combustion gasses in the coolant?
If you had the head redone, and its been tested for leaks and passed, then one of the above methods should dhow something. There is probably a good chance that there is a clog in your block. There is one way to find out for sure but it really sucks. And thats to pull the motor and knock out the freeze plugs. That will allow you total access to see if there is blockage in the water jacket. My case ended up costing me a new motor. Hope this helps, Brian
/l , [____],
Mud is your Friend :)
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