I picked up a 92 f150 with 5.0 that had been sitting for 13 yrs. It was parked for a bad starter. PO went out and bought a new truck.
I had to clean the tanks and put in new fuel pumps and fix the starter. I got it fire up today. Had to pour gas down the intake and did this a couple times to get it running but it would not stay running. Poured some seafoam in the tank and got it running. It will run at a hi rpm but lower the rpms it starts to run rough and wont idle.
Plugs are probably in need of a change. Any ideas on how else to get this sorted out? Seafoam, mystery oil down the brake booster vacuum line ann let it soak???

 

You're going to have to flush the whole fuel system and either replace the injectors or have them professionally cleaned.. I bet it will be cheaper to just replace them.

 

As said replace the injectors. Hell a set of injectors from a junk yard motor will run better at this point then the ones you have. Just make sure that they are the same color. Ford made it easy by making each type/flow injector a different color. Yours are most likely 19 lbs per hour.
A very common one. Used on many '80's & early 90's Ford 5.0 & 5.8L V8's.

 

Sitting overnight with gas full of seafoam help a lot. Fired it up today and it idles by itself. Plugging the plug wire back in helped some to. Any replacement parts are going to have to wait for now