Your lifter noise is most likely due to bad oil sump o-rings, not the lifters themselves. They're the same "quality" o-rings that all eventually leak on the turbo cars turbo drain pipe.

The oil pan needs to be removed, then all the sump o-rings need to be replaced. That should cure your noise. Don't take the car to "Joes garage" and have them guess wrongly on cams and lifters because I've heard of that happening before and they'll be wrong after much expense.

As for your check engine light, do you have any trans codes? That's possibly why your check engine light is on and you're not seeing any fuel codes.