Yep, check the fuel pressure first.
Pretty sure you have a Ford EEC-IV system in your vehicle. These are
the sensors, etc. that feed data to your truck's computer, which it
uses to control idle speed, air/fuel mixture, egr, etc., etc.
You can go to an autozone and have them scan the computer's memory for
any trouble codes. If any are present, post the results here and
you'll probably get some feedback.