'84 Westy, 1.9L WBX, Manual Trans

Runnability issues continue.  A couple of weeks ago (after replacing the ECU and Temp II sensor, and smooth running for 100 miles and good warm starting) the van was sputtering/losing power, then stopped.  Wouldn't restart.  Had my second tow with AAA Premium, this time to my mechanic.  When we off-loaded the van at the mechanic's, the van restarted...I left it with the mechanic to check over.  He identified the usual (hoses that need to be replaced, etc.), but couldn't figure out the runnability issue.  He has a very good reputation, so I don't doubt his expertise.  So he did a compression test on the cylinders.  Results were interesting and I would welcome recommendations for further study or repair:  the two rear cylinders measured 155 on each side, the two front cylinders measured 65.  So, the engine sounds pretty OK and runs OK...sometimes, and I would guess that the reason is that the compression is the same on opposite cylinders.  So has anyone experienced this phenomenon or can recommend "steps" toward a correction?  I stopped my an automotive machine shop today and was quoted about $1500 (labor) plus parts (which include cylinders).  BTW, no head gasket leaks.  Thank you.

Skip Laubach
Elgin, IL