Nissan Repair: 97 nissan pickup, two different places, vacuum line

Question
  I had my nissan looked at after it was misfiring at speeds around 60-70mph and was giving the bpt valve code.They did a tune up replaced the bpt valve,checked the egr valve and lines for clogs and replaced a sensor but im not sure which one.It still had the misfire on cylinder 4 and the bpt valve code came back  on after a while.I took it back and he put a bb in the vacuum line going from the bpt valve to the
egr valve and asked me to drive it for a few days and it seems to run fine,but two different places still could not find the problem.Any help would be greatly appreciated.thanks  

Answer
Ryan,

I would be suspect of the new bpt.  Now, if it is good I would be checking the connector and wiring upstream of it.  You will eventually have to get the truck to pas smog so I would check the electrical connection and if that checks ok then I would ge checking the EGR port for blockage.  take the EGR off and use compressed air to see that the passages are clear.  If not, clean them out and reinstall the EGR adn give it another check.