No one can help you if you won't get out there & diagnose it. The only computer you need to hook it to is a paperclip; the truck's computer will tell you where to start looking. That, a Haynes manual, & a cheap digitial multimeter are all you need to find most problems on these early EFIs. Read these captions:

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I'll even give you a shortcut: pull the driver's kick panel (beside the e-brake pedal) and smell the EEC. If it stinks like burned plastic, start shopping for a reman with the same calibration code.