GREETINGS ALL. ANYONE PLEASE HELP!
ROLLING A 96 BLAZER 4.3 VORTEC, AS IF YA'LL DIDNT KNOW. FOR A YEAR NOW I HAVE A MISFIRE WHICH THE CODE TELLS ME IS IN THE 4TH CYLINDER. FIRST I REPLACED ALL 4 O2 SENSORS. THEN ALL SPARK PLUGS. THEN ALL DISTRIBUTER WIRES. THEN THE DISTRIBUTER. THEN I HAD THE FUEL INJECTION GASKET (THE MECHANICS CALLED IT THE "SPIDER ASSEMBLY") REPLACED. NO MATTER WHAT I DO I CANT GET THE DAMN THING TO STOP MISFIRING. LIKE I SAID ITS BEEN ALMOST A YEAR SO AT FIRST IT WAS TOLLERABLE BUT NOW ITS PAINFUL TO DRIVE AT ANY SPEED. I DONT WANT TO GIVE UP ON THE BLAZER, BUT I CANT DO THIS MUCH LONGER. PLEASE HELP AND THANKS IN ADVANCE TO ANY INFORMATION. AT THIS POINT I WILL TRY ANYTHING.

 

First, hit that little "Caps Lock" button to turn it off.

Next, get a better mechanic, one that does not have his hand in your pocket already. I hope they only charged you for the parts to not fix your problem and not the incompetent labor as well. Replacing all four O2 sensors was a waste and should have never been done without first testing them. Any shop worth its salt should know how to test an O2 sensor. Couple that with the fact that the back two O2 sensors (pre-cat and post-cat) have nothing to do with engine management... And then for them to just go *****-nilly throwing parts at your expense...

The first thing that I would do would be to dump a bottle of IsoHeat into the tank. Depending on where you live, water intrusion into the fuel could be a problem. This could be from a bad fuel station or just condensation in the tank. Probably the only things I would have recommended without specific testing would have been a fuel additive and a full tune up consisting of plugs, wires, cap and rotor.

Now for some questions:
[ol][*]When you say that they replaced the distributor, did they replace the whole distributor or just the cap and rotor?[*]Does it change from when the vehicle is cold to when it warms up?[*]Have the ICM (ignition control module) and the coil been tested?[*]Does humidity or wet conditions affect the misfire?[*]Does the misfire code ever indicate other cylinders?[*]Has a compression test been performed? (would have been easy when the plugs were out)[/ol]Let us know the answers to those questions and we will work from there.