I had the same problem on my 95 Jimmy and it turned out to be a bad wiring harness connector to the fuel injectors. I pigtailed in a good one from the junk yard and it fixed the problem.
I had tried everything from new ignition module, new distributor, new wires, plugs, and coil. Even installed a new fuel pump, filter, and fuel injector spider. Still had the problem. Finally took jimmy to the dealer and they told me I had a bad connector to the fuel injector, said it was a common problem. I could have saved thousands if I had taken it there first.
GG~