Exactly what is cavitation and what causes it? I have a lund 1650 angler ss with a 50 johnson. If I have it trimmed up just a little to far it seems to jump around and “spins” like crazy, like its slipping some place. My rpm’s go up also. It seems like I have to trim it way down to get away with a farely smooth plane. JLK 
Jeff, I had the same problem on my last boat. My advice is to go stainless prop, you will never go back. The problem is that the prop you have now is flexing too much, and it is creating an air pocket where the prop is not bitting the way that it should, a stainless will not flex like that and your problem is solved. The boat will perform and handle much better. Most places will let you try a number of different props until you find the one that is the best fit for your boat(just don’t hit anything with it or you own it). The 1st prop that was recommended for my boat was perfect, they know what they are doing if you go to a good place.
Sounds like your motor is possibly set to high on your transom.Try lowering the motor by 1 hole and see if it makes a difference. 
A good quality SS prop should help
Both may be the cause. I would check the motor elevation first before spending more than $400 on a prop.
Throw a post out about the Boat, (You did.) motor, (2 stroke or 4.) and what hole the motor is mounted in. There are probably more than a few people running the same set-up you are. I would borrow a prop from a dealer as well. Try before you buy!
Tuck
Even when a boat and motor are properly set up (best motor height and best prop), trimmng the motor up will eventually cause it to cavitate and blow out. When starting from an at rest position, it usually works best to trim all the way down to get the best hole shot. Then, as the boat comes up onto plane, it usually works best to trim up to get best performance. Trimming up is sort of a trial and error process, and the exact position will vary depending on the load in the boat and the wind. If the boat starts to porpoise, you have probably trimmed up too much. Even at optimum trim position, you may need to trim it down a bit when turning sharply.
I may have misunderstood what you are saying, but it seems that your boat may be set up pretty well; and you just need to experiment more with trimming.
John, I do think you are correct. I have only trimmed the motor down about half way once! It seemed to work much better. I’ll try trimming way down and gradually bring back up. Once I get her moving she runs like a top!! Thank you all. JLK
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