Chevy Suburban 4X4 - Won't Start

I have been having trouble with my 1989 Chevy Suburban 4x4 It has a 350 with Auto Trans (TH400) 4x4 w/ TBI.  IT JUST DOESN'T START.  I mean it turns over.  It seems as if it's a car that has no gas in it.  The Fuel Pump works. The injectors work.  Just every so often it won't get spark and won't start.  HERE'S THE FUNNY PART.  I can get out and jump around scream and yell, throw things at it.  (NO Start)  Then talk sweet nothings to it.  All of a sudden it miraculously starts.  My son seems to think that if I rub the dashboard just right it will start.

What would cause this particular truck to not start only sometimes.  I have changed the module, new coil, new cap rotor etc.  All the fuel systems seem to be operating properly.  I am very mechanically inclined, I can rebuild an engine and manual trans, rear ends, etc.  This has really baffled me.  The randomness of it.  How one second no spark and the next it has spark.  Can it be in the ECM (Computer)??

I'm hoping that somebody out there has had this problem with this truck that can help me.  THANK YOU IN ADVANCE.

Take apart and reconnect all you ECM harness connections for starters.  

my dad had an '89 sub too that was doing the same thing and all he did was change the distributor, spark plugs, and wires and it hasn't done it since.