my pops has a 86 ranger with a 2.9. And what its been doing is, itll start up just fine then u give it a minute and itll start to run very rough like a bad miss fire, then if he revs it up for a bit. itll clear out and then run just fine untell he starts it up again and it seems to do it more the colder it gets and it smells very rich. Iv checked the injectors and there fine, what other things could it be ? O2 sensors oorrr

 

The PCV with a new hose fixed mine today. A very likely culprit, if it has one, could be the IAC. Good luck

 

I had a 1961 F100 that acted like that. The problem with mine was the automatic choke would open too slowly. It would fire up nicely but then as it warmed up the choke would still be closed so the mixture was WAY too rich. I could open up the hood and flick the choke open and it smoothed out and I was on my way. I know that's an older era truck than yours but maybe it's an idea to consider. Best of luck to you.

 

May want to pull the dist cap and check for cracks, and see if the carbon button in the center is worn off, also check the rotor cap.

 

yeah its not the cap and rotor those just got replaced and couldnt be the iac because it dosnt stumble like a low idle but more like a missfire , and how would a PCV valve give me this symptom ? cus yeah thats a easy one

 

FYI my problem came back. The PCV did not fix it.