Replaced crank sensor and timing belt two days later is running poorly

What was the starting issue you had? What was the reason to replace the timing belt? Mileage or did it fail? I would have done a tune up at the same time myself if the plugs and such have unknown miles on them. Mainly because they would be an unknown item. Also a throttle body cleaning to ensure proper idle. Beyond that it is hard to say as parts can easily fail or it could be as simple as a loose connector that was removed when the other work was completed and it now is showing up. Exactly what do you mean with "running awful" misfiring, low power, poor mileage, doesn't start properly? Those may tell us more information.

Okay, if the parts were replaced for age and not failure but it was running good then they may not have touched the plugs to prevent issues. The owners manual info on that vehicle shows the plugs are a 60,000 service item. So at 112,000 if they were not changed they could easily be the issue. However they are known for the wires and coils as well.
To change them requires that the intake plenum be removed to gain access to the plugs, like many newer cars. The book shows about 2.5 hours of labor for the job. It's hard to say if they are worn out or if something else happened, What you might want to do is take it to a different shop for a second opinion. They should be able to tell if the parts were replaced or not. Might even ask a couple other places for prices on the same work. As I don't know the thoughts of the other shop I don't know what they did, however if they charged to for the tune up parts and now they think those are the problem now, it would depend on what they warranty and what they showed on the bill.

If you want to see what it takes here is a video on it. Shortened a bit in editing so you don't see the entire process.
https://www.youtube.com/watch?v=So17kyOkwIU

True but it took 2 days for it to start running bad, timing belt should have showed up in the first ten minutes of driving.