Couple issues with 350TBI... related?

[TwoFiftyShifter]

My 87 has the 5.7 TBI motor, and has a couple issues.... first the idle fluctuates alot of the time, 500rpm-900rpm and so on, I think it's the intake gasket. However, the truck is either burning or leaking oil. I burnt a quart in 50 miles today.... this happened tihs summer, anjd I got underneath and tightened the oil filter more (probably too much) and its held oil since. I changed the filter lip too, so that's not the issue.... It isnt smoking like crazy, it doesnt leave any puddles on the ground, I just want to know what it could be.