My 89 d100 5.2L 318 has been running perfectly since I got it. The past couple days every so often it wouldn't idle properly. So after it stalled on me three times on my way home I checked the codes. I came up with
17,34,52.
I assume 17 came on because it was very cold this morning and I didn't have rime to fully warm the engine like I normally do.

But I don't understand 34. And how do I check the air fuel ratio???

 

The code 34 is a problem with the Speed control Solenoid circuits possibly a problem with the AIS motor or one of the three solenoids on the top rear passenger side of the engine.

The code 52 is a too rich fuel condition and I would first look at the injector spray pattern.

 

As far as the solenoid goes, is there some way to test it to be sure??

 

Unfortunately the AIS requires a special tool but rarely goes bad. I have never seen one fail.
All three solenoids can be tested with a hand held vacuum pump or a vacuum gauge and rerouting of vacuum lines. The front solenoid of the three controls the EGR vacuum and that can cause what you are experiencing so I would look at it first. A code 34 can cause a code 52 so I would zero in on the code 34 first. When it is idling improperly try pulling the vacuum line off the EGR valve and see if the idle smoothes out.

 

Thanks so much SEAL. You always have all the answers to my questions, it makes asking for help a painless process.

 

Update: the egr is fine. Truck has been alright for the last 2 days. I can't find any vaccum leaks so I'm baffled again. On top of that, all last week my gas milage has been crap but it was good today