Truck Repair: excessive smoke. intermittant miss on # 1., oil pressure loss, diesel mechanic

Question
I've been working on a 10/93 L10-300 with STC cpl 1558 which I've tried everything the troubleshooting manual asked to check and still have the problem.  Everything I've tried including setting the overhead (which i've done at least 3 times), check the stc set points, excessive oil pressure loss at injectors, oil pressure to the injector tappets, check fuel return restriction plus more has all been done entirely following the t&r manual for my specific engine.  I've been a diesel mechanic for at least 15 years and its extremely frustrating not finding the problem.  All the injectors were replaced and the problem still continued.  I tried swapping the injector with another hole.  same problem.  the miss isn't as frequent now but it smokes like a pig.  Mostly white  smoke at idle, hi idle and especially under load.  some brown smoke is apparent too. and it has great power .  A year ago I noticed no. 1 missing and found a bad injector lobe for that hole.  I replace the cam and injectors,  had the head rebuilt and replaced the piston rings and bearings.  It only had 117,00 miles. upon 1st firing it up no. 1 was still missing.  now the miss comes and goes but it still smokes alot.  I noticed someone earlier questioned you about a similar problem.  You recommended checking for a check valve on the oil delivery side of the stc to the tappets.  I checked and I think this stc valve has a check valve in the outlet elbow fitting for the oil delivery line to the injector tappets.  I might be wrong.  I'm at the end of my rope.  I don't know what else to do.  Can you please help me.  thnx.

Answer
Did you use the tappet tool when adjusting the injectors?If not that might be the problem.Is there a small hole in the metal oil tube at #1 injector? This was put in later to allow for air to escape from the oil manifold which will cause smoking until you rev engine to shift the STC valve.