GMC Repair: Throttle body, gmc sierra, fuel rail

Question
93 GMC sierra is running rough at times,seems to be only four cylinders,then will be o.k. for a while.Checked fuel filter and fuel pressure.I have fuel spraying out of driver side injector but not the passenger side,I checked for voltage at both sides and get a reading of 11.5V d.c. Do you have any ideas for me?

Answer
I would check for blockage in the passenger side fuel rail. no fuel on passenger side at all? with a vehicle that is a little older I would check each and every injector and fuel rail on the good side to confirm it is good. meaning disconnect the good and hook up the bad side and check it.