honestly on such an old engine its pretty inevitable that the vac lines go, so if you havent replaced them yet i suggest you just do that and have peace of mind that the vac lines are new and not leaking.

 

lmfao! you'll see the car jumping down the road lol

 

if you have a leak in the hoses you should get a CEL.
i think comman codes are..
running too lean trim bank 1 and/or 2 (ive had both on at the same time once becuase2 of my vacume hoses split open at once.=\ )
or an air leak after the air intake code.