electrical interruption at 1800-2000 rpm

[ken-r-mer]

I've been running a Megasquirt 2 v2.2 for about 5 years w/ no issues. Recently I've developed a stumble in the acceleration ONLY between 1800 - 2000 rpms. Below and above those rpms the engine accelerates smoothly. How I have initially determined as it being an electrical issue is a brief interruption in my CD player between the 1800 and 2000 rpms. On my laptop I also noticed a jump in my air fuel ratio to well above 16 between the 1800 and 2000 rpms (electrical shorting causing the fuel pump to sputter?) too.
My setup:
Flathead V8, 12v system, 2 - 1988 Ford Escort TBI's on an Offenhauser super dual intake, Mallory Unilite distributor, Mallory Coil, Mallory Hyfire 6A Microprocessor Controlled CD Ignition, electric fan, electric fuel pump.
I tested with the radio/CD player off, the electric fan off, the headlights off...no change.
I verified the grounds are tight (both from the engine to the frame and the battery in the trunk of the car to the frame)
I've had my alternator tested, runs as expected
Pulley belt is tight, no slippage.
Battery is within specs.
Dash amp gauge reads between 13-14 at idle
I replaced the Mallory Unilite module with no change.
I replaced the Mallory Coil, no change.
I replaced the broad band O2 Sensor, no change.
I replaced the vacuum hose from intake manifold to the MAP sensor in the ECU
Fuel pressure is at 15 psi (within the 13-17 psi range for the 2 TBI's).
Replaced the dash tachometer fuse just in case it was not functioning, no change.
No blown vehicle fuses
Still trying to fire out how to test the Hyfire 6A Ignition
My BIG question NOW: Is there anything inside the Megasquirt ECU that could cause the unique problem, such as, have the MAP sensors been known to go bad or has the 5 volt regulator ever gone bad?

[Matt Cramer]

An RPM dependent issue isn't likely to be inside the ECU. Can you post a data log of what's going on, along with your tune file?