Bad miss above 3500 RPM

[DemonRod]

I just had an electrical meltdown on my 72 Demon with a 408 stroker motor. I had to replace the engine and forward light harnesses. I bought a year one harness for a 73 340. I replaced the harnesses and fixed the cobble issue under the hood (before I bought the car and was hid well under tape) but now, when I reach 3500 the car starts to miss pretty bad, the Tach gets VERY erratic and finally stops and holds at 4000. The only thing that the direct short fried was the voltage regulator. I am running the chrome "brain box" from Mopar Performance and it seems fine but............... I am at a total loss as to what is going on. Any suggestions?? Any help would be GREATLY appreciated!!

 

[805moparkid]

sounds like the ecu

 

[DemonRod]

Thanks! I was wondering if maybe that was it. I have an orange box I will put on and see if that cures it.