Hyundai Repair: mechanical mystery, hyundai excell, rocker shaft

Question
I have a 1986 Hyundai Excell GL.  It's a four-cylinder with the smallest displacement of 1500cc.  The car has a total of 175,000 miles on it. The engine was rebuilt 72,000 miles ago.  I had new cylinder sleeves put in at that time.  The cylinder head has been resurfaced twice.  The last time .008" was taken off.  My dilemma beginns when I change my oil with Valvoline Max Life 10W-30 motor oil. I only drive 32 miles with this oil in my engine, since I lost power while driving on the interstate.  I put regular Valvoline 10W-30 motor oil back in the car.  I let the car idle for a few minutes and drive it for maybe 350 feet to the bottom of my driveway.  There I sit in the car and occasionally rev the motor to 1300 rpm to help warm up the motor.  All of a sudden I hear a clashing noise, like a connecting rod cap falling off in the engine.  I took the oil pan off, found nothing unusual.  The torque on all the mains & connecting rods checked OK.  I took the connecting rod caps off numbers 2, 3, & 4.  Did not find a spun bearing.  Have yet to take off number 1, as it's giving me difficulty.  I have put a socket on the crankshaft nut and rotated the engine 360 degrees clockwise and counterclock-wise.  Each time the engine gets stuck when numbers 2 & 3 cylinders aproach top-dead-center.  I had my father help me while I was rotating the engine from underneath the car.  No rocker-shaft bolts came loose, the valve keepers were in place, no broken springs  -- the valve train seemed to be moving the way it was supposed to.  I also had the flywheel cover off to see if there was any binding there.  My next step would be to take the timing belt off to see if there is anything broke on that side of the engine.  Can you provide any suggestions as to what you think it might be?  During this test I did have the manual transmission in neutral, but I did find the dust boot on the outer right hand side driveaxle was missing.  The wheel still rotated though.  Thanks in advance.

Answer
Unfortunately, you'll probably need to continue pulling stuff apart until you find the issue.

Before doing any serious looking inside the engine, however, do your best to check the external possibilities.  Although your description (binds only when 2 & 3 at TDC) leads me to believe you don't have an external issue, these things are typically easy to check and require much less work than pulling the cylinder head.  (I'm assuming you've reinstalled the removed bearing caps.  If not, the connecting rod can jam between the cranksjaft journal and the cylinder wall.)  Remove the belts to verify that none of the accessories are binding.  Check to see that nothing is contacting the rear side of the crankshaft pulley, preventing it from turning.  Jack the front wheels off the ground to help verify there's nothing binding in the transmission.

Presuming you don't find anything wrong in the checks above, your next step is to get the #1 rod bearing cap off so you can check that bearing as well.  If you find nothing there, you're up to removing the cylinder head.  If you've got access to a boroscope, you might try looking at #2 and #3 cylinders with that prior to pulling the head.