Act after six months

 

Ooooo... That will cause some problems. Without knowing the temp the engine won't know whether to make it run leaner or richer based on the ambient temp and incoming temp. I know there is a resistance chart for those based on ambient temp if its in spec or not.

 

Is it normal for all of that black crud to be in there?

In the lower plenum?

 

No, likely you have a bad PCV or something trapping in all the buildup in there, valve guides or maybe rings. Are you burning any oil?

 

I replaced the pcv not long ago. And no the engine uses no oil at all between changes

 

Check it again and if possible clean it, the oil had to come from somewhere or likely was in there from 6 months ago from the old PCV. And I see you did a compression test and they all held. Next step would be to run a throughout seam foam treatment or disassembly and cleaning.

 

I'll check the pcv tomorrow. It's possible it could be from before. This truck sat for years. And was neglected before then.

I've seen different methods to seafoam an engine. Do you any preferred methods?

 

1/3 in the booster vacuum tube, 1/3 in oil and the rest in the fuel is how most people do it but I usually go half and half in the tube and oil.

 

I've also heard you should change plugs afterwards?

 

Inspect them, if they are clean then they are okay but if they are fouled up with allot of carbon or the electrodes are burnt to a crisp then its time for a tuneup.