I have an 06 grand Cherokee 3.7 that seems to stall at 2500 rpm. The check engine light is on and reads catalytic converters, cam, and crank sensors. Ive replaced all 3 including cam and crank sensors twice. Also replaced the pcm. After computer reset it would quit doing it for a day or so and then start back. Since replacing pcm i can start and rev it to see if its doing it and if it is I can shut off and start back up and then it runs fine excpet check engine light is still on. The check engine light goes off from time to time but mostly stays on. I'm lost as I don't know what else to do.

 

I had a very similar issue-At 2500 RPM highway speed the vehicle would shutter slightly. The DTC was for the converter. The check engine light would come on and go out for long periods of time. The converter was stopped up and not allowing the engine to exhaust. Eventually caused a failure to start and run until cool off (back pressure relief over time).

A difficult way to test this would be to pull the o2 sensor and put a pressure gauge in its place. If the gauge reads greater than 2 PSI then you could conclude something was creating the back pressure. I've never tried this but have only read about it. This problem was very difficult and slowly failed over about 6 months.

I would think a vacuum gauge on the manifold could also test for a plugged exhaust. I hope you find the issue soon and this helps.