No acceleration

I have a 94 f150 5.0 with 80k. The truck
was running well until last week when it
died three times as I was driving home.  I  
contacted the local auto shop talk radio
show and was told the three most likely
problems.  The TFI, the pickup coil or the
ignition switch.  All three parts have been
replaced.  The engine will start and Ru at
idle but will not rev when the peddle is
pressed.  Fuel pressure checks at 40 psi.
Any suggestions on what to check next,