Cummins ISM idling out of control

I've posted on here about this problem before, but I have more knowledge on the subject, and have done some more tests on the problem child than I did back then. The engine is a Cummins ISM CM570, in a 1999 International Paystar 5000. Kind of a mix of parts here, the engine is an ISM 330 with CPL 2608, the ECM says ISM 450 when hooked to INSITE, and it is set up at 400 hp and 1450 torque. The problem I am having with it is that it will idle way out of control, as high as 1400 rpm at times. Using the cruise switch to adjust idle does nothing. INSITE says that the idle validation circuit says "no" no matter what position the throttle pedal is in, and the signal wires to the pedal for the idle validation circuit read 9.49V however the position circuit reads 5V. I have verified that the throttle pedal is not the problem using a multimeter, and a new throttle pedal. The strange thing is that this engine has been replaced, but the ECM was not. The old engine had the same problem, and when the engine was replaced, it was fine for a while then slowly worked its way into it. Then it developed a misfire about 5 months ago and all 6 injectors were replaced, which cured the high idle problem, and allowed the idle rpm to be adjusted. Or so I thought. Now it is doing the exact same thing, idling high and out of control. Could the injectors be bad again after only 5 months of use? Or is there something else going on here?

 

Forgot to mention that I did that as well. I'm thinking now that it might be ECM related since that's the common denominator between the 2 engines and I don't think the ECM ever is supposed to put out a signal voltage of over 5V, is that correct?

 

The engine isn't slanted like the old leaning tower of power, except when the motor mounts go bad due to the clutch being extremely grabby

 

No codes, and the ground pin for the connector to the pedal is grounded properly