I have a Gun with 525's and am running 32 pitch props and after about 4500 rpm the throttles start separating and after 5000 separating even more, quiet a bit. To keep the rpm's together the throttles are way apart. Is their some kind of adjustment or maybe it's a stretched cable, man it's very frustrating. Any of you guys ever had this problem, and if so what the heck do I do?

How many hours on engines?

cables may be stretched, how old are they?

With both engines OFF and flame arresters OFF have someone hold the throttles full ON and see if both throttle plates are full open and then have them hold both at different settings and see if they are the same angle. If they are off the same amount throughout the travel than adjust the one that is closed more. If they are the same at part throttle but not at full than it could be one end or the other is not mounted in the right hole causing more travel on one.

42 hrs on complete rebuilds

Could also be a potential issue with your props being somewhat mismatched from minor damage, blade tweak etc..

did it do this before the rebuilds ?...........one engine may be down on power

How about a bad Tach? I would check the RPM at the engine and see if it matches the dash. I know one of mine is off but the sticks are not.