overheat only over 3000 rpm

once you are at about 30+ mph, the fans are not accomplishing anything except potentially slowing down the air flow through the radiator. So better more powerful fans will not solve your problem. look to one of these other suggestions as a solution.

4 fans is a lot of fans to fit on a Mopar radiator core. Can I ask what size they are? If they are less than 12" each, they are extremely inefficient and you'd do much better with 2 12" fans or go back to mechanical fan and shroud setup. Again, this advice is for speeds under 30mph and the idea that you will have less blockage for higher speed driving.

Finally, It would be nice to find the exact reason for the 3000rpm issue but It could be that the heat generated by the 3000 rpm's is just too much for the volume of fluid you have in your system. A larger radiator with more volume could solve some hidden issue if you start running out of other solutions.