'89 240 #3 cylinder not firing

[LoveMy240Wagon]

I've been working on this problem for quite some time now with no luck.

My wife was driving when all of a sudden the engine started running rough.
She drove it 40 miles home and said it was very underpowered.

The dipstick smelled of gas so I drained the oil and it had a bit of gas in it.

I discovered that I could unplug spark plug #3 and there was no change in running.

Cylinder number 3 is not firing. I check the exhaust manifold temp's and sure enough, #3 is cold.

Checked spark (multiple times)- just as strong and blue as any other cylinder.
Checked compression- 150psi across the board. (Min. is 128psi w/ 28psi max. variation cyl. to cyl.)
Pulled injectors- fuel sprays the same amount from each injector, the resistance checks out 15.7ohms, voltage while cranking checks out too, grounds are good, no wires are crossed.

Not one single code from OBD (both circuits all clear 1-1-1) or CEL on the dash.

R&R'd injectors just because I had spares.
New intake manifold gasket.
Swapped FPR's
Removed intake manifold and verified intake valve opening at correct time.
Checked timing belt timing (probably 3 times).
Removed exhaust/cat to verify not plugged.
Swapped MAFS.
Disabled cold start injector.
Swapped ECU's.
New plugs/wires/cap/rotor just to make sure.
Recent crankshaft position sensor or engine speed sensor whichever it is called.
Recent fuel pump/filter.
Probably did 12 other things I forgot about already and nothing, nothing at all!

Fuel + Spark + Compression = Ignition so why in the world won't #3 fire???

I hate to have to take this to a shop just so they can throw parts at it, I don't know of any 240 specialists around.

Any ideas where to go from here? I'm stumped.

[LoveMy240Wagon]

I considered that.

But wouldn't there be some evidence of that backpressure through the intake?

Well I suppose it could get sucked into the other cylinders.

And how could the exhaust valve not open? I can see the cam pushing the lifter. If the lifter collapses?

Hmmm....

[LoveMy240Wagon]

I did get a look at the intake manifold and it is clear.

The exhaust manifold however...

I might end up taking it off, why not, took damn near everything else apart.

I'd pull the head but I have a feeling that I wouldn't find anything out of the ordinary.

Maybe I'm just getting cynical.