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random misfire can be due to bad sparkplug wires or a vacuum leak at the intake, there are many thing that can cause a random misfire even low fuel pressure, and last would be dirty injectors. i would start by having the fuel pressure checked and then having the injectors cleaned.
I think I may be able to help you, but first we need to clear a few things up. Is it getting spark or not? If it is getting spark, why are we testing the ignition module? The next question would then be how did you go about determining that it is getting fuel? Have you tested your fuel pressure? If so, what was the pressure reading? Did you check for injector pulse to make sure that the Powertrain Control Module (PCM) is able to fire the fuel injectors?
Also, you are working with an engine where the ignition timing and the fuel is controlled by the PCM. Have you scanned the PCM for fault codes? If so, what codes did you get?
If you do not know the answers to these questions, or if you do not know how to do this stuff, post a comment to let me know. I can give you step by step instructions on how figure this out. These questions MUST be answered before anybody can give you any REAL help with your problem (Although many may try to "guess" - which rarely works and usually turns out to be VERY EXPENSIVE!).
Thee are a couple of things left to check. One is to hook up a fuel pressure gauge to the fuel rail and see how much pressure your getting and compare it to specs. It maybe getting fuel there but not enough pressure. To see if the injectors are being pulsed you wil need a set of noid lights. You will unplug an injector and plug in the noid light. It will flash everytime that injector is pulsed. If it never flashes your injector drivers on the ecu are bad.
Maybe needs new fuel filter, possibly new fuel pump. Check fuel pressure, low fuel pressure would indicate a problem with fuel filter or fuel pump. If fuel pressure is sufficient, fuel injectors may be shot. Use a stethoscope, or screwdriver, to listen to each injector to check for a clicking sound, signaling that the injector is operating.
first of all you have no carb its fuel injected, at least you know you have spark, now do you have fuel pressure??, is the fuel pump working?/ if you have fuel and pressure then you have to check signal at the injectors, so if you have fuel pressure and a good injector pulse the next step is to check the injectors, this may require removal, good luck
even if you have preasure in the line that does not mean you have fuel going into the engine. you should check the injectors to see if they are spraying and if not you need to check the injector pulse to find out if the PCM is sending the signal to them to spray. to check injector pulse you will need a noide light to test the pulse it the light lights up you have pulse, but easy way to check is pull an injector and turn the engine over see if it sprays.
You need to check the oil with the dipstick (wipe in down a few times) to see if it looks like a chockalate milk shake. If coolent has made its way into the oil you have blown head gasket. The fuel pump which is usually in the gas tank in most gm vehicles would not cause white smoke, if it failed you car would not start because your engine would not get any gas to the injectors
You need to use a LED type test light for the injectors or a Bosch style Noid light for the injector. To test the cam/crank sensor signal you either need a scanner to read them or a lab scope to show you a signal. The pickup plate in the dist handles the injector timing, the crank sensor provides a RPM signal. They both feed the computer information for ignition timing. Good fuel pressure, injector activity(Noid), and good spark out of the coil. The coil is what I replace the most of.