86 Blazer rough running and vibration

I have an 86 full size blazer that sometimes runs rough and sputters thru the exhaust and has no power. it doesn't do it all of the time. sometimes it vibrates like the u joints are bad but not all of the time. while having to wire up the exhaust that decided to rust away to nothing i also noticed that it seems dry underneath. i haven't worked on an old 4x4 since i was 21 and quite working on cars when i was 25, that was a long time ago. were and what should i grease up.

i put on a new cap, rotor, plugs, air filter, fuel filter last fall and it still does it.

the blazer history might help: i pulled it out of a guys barn last summer. it sat there for 5 years being driven 1-2 times a year.

set the timing again with a timing gun with the timing wire unconnected ?

PCV valve changed?

Cleaned the Throttle blade?