Hi there. I have an 88 5.0 that I have fixed a ton of wiring on. I got it to run but not well.. never really even drove the thing. A week ago, it ran long enough that, i was able to pull the koker codes.Now the rpms are dropping and it's choking itself out. this happened after a weeklong cold snap. The plugs and 02 sensor are Fouled!.
21- ECT out of range
22- Map out of range
42- Hego voltage high/sytem rich
33- EGR not opening
13- rpm low at idle
Theres a new 02 sensor, the Map is new and the Ect is new... the commonality in these circuits is the blk/wt wire. But why wouldnt the tps and the power pressure steering switch be throwing codes too? ive chased that wire and thought I had it licked. just want to make sure im not missing anything before i go unwrapping stuff. Thanks!

 

Do you have any kind of voltmeter to use?

If so, there should be a 5 volt reference voltage going to each of those sensors. Do you have that reading?

 

Yep... getting reference. the crazy thing is, when i was troubleshooting before, I checked all the sensors and wiring. I did take off the egr and it is disgusting so i'll get a new one. do you reckon I should pull the line that connnects the egr to the engine and clean it too?

 

Might as well while you have it all open.

If the EGR was stuck open it could have contributed to pulling the VREF down resulting in all those codes.

 

Changed egr and solenoid and egr sensor that mounts to the valve... now I'm pulling a 31, 21,24 koeo... I hate this truck right now

 

There is a DPFE sensor that was pretty troublesome and you might consider replacing that part.
DPFE = Delta Pressure Feedback Sensor.
It works with the EGR system, but when not working correctly can produce the symptoms you are getting.
It gets full of carbon, the small hoses get overheated and crack open, just plain troublesome..
It is usually located behind the EGR Valve. If you purchase a new one , you will not have any problem finding it in the engine compartment.