Hey folks. I've been having a stressful problem with power cutting in and out while driving. I have no confidence to drive far. Any suggestions would be very very much appreciated. The symptoms:
I'm losing and gaining what feels like 100 horsepower over and over every time I take my car out. It's drastic. It happens at any speed, any temp, any type of acceleration except wide open throttle. Generally wide open doesn't lose power. When the power cuts out, the engine is definitely running a bit rough. When power kicks back in, everything smooths right out. There are no variations in how much power I lose and gain. It's always the same.

1972 Monte Carlo
'75 454 BBC fully stock
Sniper EFI (I've exhausted all possible causes related to the Sniper, including sending it back to Holley, removing EMI/RFI, fuel pressure, fuel tank venting, etc etc)

​​​​​​I believe the problem is possibly a bad cylinder. I'm not a mechanic but I have learned a lot while troubleshooting this problem. How can I know if I have an actual internal engine issue that is causing this?

 

First, is the efi matched for this engine? You suspect a cylinder, can you do a compression test on all 8?

 

EFI is perfectly matched to this engine. I can research how to do a compression test.

 

What fuel pump?

 

Holley 12-920 Fuel Pump.

 

I realize this is a 60 psig pump, and perhaps at wot you are having the lack of power issue, check the mechanical linkage for slop, also, perhaps a trim rgulator set to 60 psig as to streamline the fuel flow from the pump.