I got this from a buddy, after it had taken some front end damage. I've wrenched some work into it, but I'm not quite ready to pass smog for the title transfer. I was hoping to find someone who tackled these codes themselves or even someone who has any suggestions or quick-fixes that could help clear them up. I believe the codes are # 0075/0300 which should be System too Rich, and Random Misfire. Someone here suggested that the misfire may be caused by a vacuum/intake leak, dirty maf, or bad injectors...going to check these out today and hopefully get to the bottom of it. I only put about 10m on it since the recent upgrades and fixes, so I may just cruise it around a bit and see what happens first.

I just replaced the serp, ALL filters and fluids, cap/rotor(b&w), ignition wires(b&w) and plugs(acdelco). I fixed a leak going to my center-dash vents, while patching up some weathered wires with 5/32 7/32 cuts that I had laying around the garage. It has cooled down considerably ( not quite 210, where I'm told it should be roughly ) and lost most of the vibrations I was having in the front end. But the service light kicked back in after about 5 minutes out, and I'm pretty sure all sensors are where they should be...The truck didn't have a fan shroud when I bought it, but I have the upper shroud already on it's way. The plug from the hood light has also been pulled out intentionally due to the ground wire being completely disconnected. I noticed that the fan blade seems to sway towards the radiator a little bit, it spins straight but something seems a little loose or worked, and I don't think it's the pulley.

Anyhow, I'm dying to get this engine where it should be so I can work on a real audio system. Thanks in advance for any tips or advice, glad I found a real discussion forum for her!

 

The misfire code could be happening if the clutch fan is slowing down the belt/crank any amount. Misfires are detected by the crank sensor at the bottom of the timing chain cover, if the sensor detects any slowing down for just the slightest of moments then it will store a code in memory if the misfire does not go away after a specific amount of times then it will set a code and turn on the SES light...

The system to rich could be the MAF sensor or the IAT(intake air temperature) sensor. The IAT tells the computer the incoming temperature of the air and adjusts the fuel mixture, if the sensor thinks the air is colder then it will richen up the mixture, if it is to warm it will lean the mixture out...

These problems might also be related to your fixing weathered wires if the wires are related to the sensors needed to set these codes, you might have some bad connections or excessive resistance in the splices that you made to fix the wires and the extra resistance is confusing the computer into setting these codes....

Hope this helps you