The simple things first: Using the Helm manual flow chart for the fuel pressure test, section 6E = Driveability & Emissions, if you follow the chart you will know that both pumps are good or which is bad. If the pumps pass muster, I would scan the motor running in open and closed loop. The block learn numbers and the O2 readings will tell you which way to go if the injectors are bad, or it may turn up something else. The scan will also let you see any codes, present or history, which could aid in diagnosing the problem.
Nothing much can be said before you have some data and have run some tests. The general direction of bad fuel filter, pumps, injectors trouble, plugs, wires, coils, gets refined after following the Helms manual flow charts for trouble shooting.
I'm only saying this because it is better to follow the manual diagnostic charts than guess. The senoir guys like Jeffvette and Bell Curve gave you the most likely suspects, now you have to do your diagnostics starting with those systems.
Tom