M42 feels like it hits 4k rev limiter when it gets hot

[sbarton]

I've got an M42 swapped into a 1874 2002tii.  It runs fine when cold, but when it gets hot after running hard for 30-60 minutes it feels like it hits a rev limiter at 4000-5000rpm and get worse if I continue to drive it,  If I let the car rest for a bit and cool off, it is fine again. 

I've swapped the ECU, Coil Packs, AFM/MAF, and even the entire motor with engine wiring harness. 

I'm pretty sure it is electrical since it only happens when it is hot.  Any ideas/suggestions?

Thanks! 

-Scott

[wazzu70]

I agree it sounds electrical. I would check all your sensors to verify they are working properly. The testing procedure for most of the sensors is in the bentley.

I would check crank and cam sensors, coolant temp, throttle position and AFM/MAF to start.

[sbarton]

Problem is that the all sensors are on the motor and I swapped motors.  So essentially different sensors, same issue. 

-Scott

[wazzu70]

That does not mean all the sensors are goving the correct signal though. Did you change wiring harnesses as well?