After what you have done aleady I would test the injectors just like you say you are. Have you check the computer codes? it may lead you in the right direction too. Does it miss when it is in idle too?
Have you looked for vacume lines detached? How is your fuel pressure? have you tested piston compression? The book also list incorrect ignition timing as a possiable cause. I might also look at having the ignition module tested and the ecm after that (testing them is free at any autozone).