skull crushers with w bar is what its giving me most problems, which other exercise is as good as that one, to replace it?
Skull crushers is a classic for creating elbow probs, and is not nearly as effective as lying extensions for size.
First of all after taking a break from skulls to let the elbows heal, then try extensions instead, since they're the best for size. Lower the weight well below the bench, getting a good stretch. It's also ok to cheat a little from the bottom to get the weight moving.
Doing this on a slight decline can also help remove elbow stress.
Also try different bar grips-E-Z curl bar, triceps hammer bar, or 2 hands around the end of one dumbbell; can be easier on the elbows. Or try lying extensions using a low pulley and rope attachment.
On top of that, ensure that these are done after some other compound triceps exercise is done first, something like close grip benches or dips.
Keep the reps moderate to high, 8-12 reps or so, and rests between sets at max. one minute, to keep the area warm.
If lying extensions can't be done at all, use the high lat pulley when facing in the other direction to do extensions.