Note: The following procedure is based on the assumption that the fuel pressure is adequate.
1. Check all electrical connectors that are related to the system. Check the ground wire connections on the intake manifold for tightness. Loose connectors and poor grounds can cause many problems that resemble more serious malfunctions.
2 Check to see that the battery is fully charged, as the control unit and sensors depend on an accurate supply voltage in order to properly meter the fuel.
3. Check the air filter element - a dirty or partially blocked filter will severely impede performance and economy.
4. Check the related fuses (probably not required in your case). If a blown fuse is found replace it and see if it blows again. If it does, search for a grounded wire in the harness.
5. Check the condition of all vacuum hoses connected to the intake manifold.
6. Remove the air intake duct from the throttle body and check for dirt, carbon or other residue build-up. If it's dirty, clean it with carburetor cleaner spray, a shop towel and a toothbrush, if necessary.
7. With the engine running, place an automotive stethoscope against each injector, one at a time, and listen for a clicking sound, indicating operation. If you don't have a stethoscope, place the tip of a screwdriver against the injector and listen through the handle.
8. Disconnect the injector electrical connectors and measure the resistance of each injector. (Measure the resistance of each injector across the two terminals of the injector.) Resistance should be 11.3 to 15.7 ohms at 68 degrees F.
9. Turn the ignition key On and check for battery voltage at the voltage supply wire terminal of one of the injector harness connectors. If battery voltage is not present, check the ASD relay and related wiring. NOTE: The fuel injector voltage supply wire could be either dark green/black, dark green/orange, or dark green/light green depending on model. The voltage supply wire is always the same color at each injector connector while the injector control wire color is different for each injector. (Again, this is only included for the benefit of others having fuel injector problems.)
10. Install an injector test light ("noid" light) into each injector electrical connector, one at a time. Crank the engine over. Confirm that the light flashes evenly on each connector. This tests the PCM control of the injectors. If the light does not flash, have the PCM checked at a dealer service department or other properly equipped repair facility.
Having said all that, a friend of mine had similar problems with his 96 Laredo. He told me he always used the cheapest gas available. I had him switch to premium, and his problem went away quickly. Apparently his injectors were merely dirty.