what would cause hesitation/vibration?

Well it's hard to say since the light isn't coming on. But if it isn't a major misfire then the light may not come on. You could be getting not enough or too much fuel in random cylinders. Causing misfires. But with rough idle I'd have to say it's most likely a misfire. I'd do a compression test and a leak down test on the cylinders if you have the tool. I'd probably cost an hours labor at a shop to do that. But you can also take out the spark plugs and look at them. I'd there clean put them back in. If they smell heavily of fuel. Or are really dirty ten clean them and put them back in and see what happens. It could be the injectors are putting in too much fuel. Does it run rough at high rpm. And as for the maf sensor. Very possible but again why's the light not on. If it hasnt done it very long or if it's inconsistent it may not throw a light. Also take the maf off and look at the two coils inside. Blocked by something? Broken? Check it out and let me know.

air ilde motor it will be chrome about the size of a pill bottle on the intake manifold