When im running about 80-100% of throttle I can hear my prop losing bite every few seconds. Sometimes if the weight distribution is wrong or the waves are just right it will lose it bad enough I have back off the throttle and let it get going right again. What may be causing this?

Number 2 is I have an aluminum prop and I run in a river a lot of the time. The sand is starting to make a shallow depression in the prop, and I know eventually it will ruin the prop. Would a stainless steel prop be worth the money for this motor and be a solution for this problem? The motor still runs good and has never had any major repairs.

Finally, what type of maintenance do I need to do on this motor besides lower unit oil changes? This is a 2 stroke motor. Thanks for any and all help.  

Sounds like you have the motor too high on the transome.   A banged up prop will add to the problem also.  

If your'e running lots of rivers and constanly banging the prop you may want to stick with the aluminum and keep a spare.  The Stainless will perform a lot better but it cost a whole lot more to get repaired and it's a lot more likely to damage the LU internal parts

Maintenance depends on how often you use it.  Water pump should be replaced every three years.  LU lube changed every six months and grease any fittings.  If it sits long periods between use, fog motor and drain carbs and purge fuel system.

I don't know of anyway to adjust the motor height, its not on a jack plate or anything like that. Ill get a spare and carry a wrench like you suggested, I kind of had the gut feeling a ss prop would tear the motor up since it wouldn't give.

Are you trying to run a short shaft motor on and 20" transome?  

The anticavitation plate should not be much more than an inch or so above the bottom of the transome.

No I am not.