If it became a problem at 3200/3500 rpm and full boost the reason it would clear up is because even though the rpm is higher and the boost is the same the cylinder pressure is lower because of the rpm. Spark blow out would be most likely on a stockish set up at the point of peak torque. That should be around the rpm where his problem is happening.

The ranger cam is a down grade. Its lower lift then a stock turbo cam. The roller portion of the cam doesn't really pick up much. If you decide that you have to do the cam just be sure to mark your sliders so you can id which one went where. Put the cam in a plastic bag and oil it up so it doesn't rust while awaiting re-installation.

Seriously if you go to the ranger get an adjustable cam gear so you can play around with the power band enough to get some of your top end back.