Reply to "Help... EFI Engine problems"

Well, that is a hoot. Seems like the sensors are reading OK. Manifold pressure and throttle position seems to be in check throughout the pull. Somehow you are hitting an instable state where the computer is over correcting and bouncing around.

I have the same fuel pump and similiar MSD setup. What is not clear is the type of distributor. Do you have a electronic distributor that the Haltec controls? IF so, is the distributor in good shape and not changing spark advance or dropping an cylinder creating a mis-fire? A worth while check.

Look at the fuel map again if you have a lean out condition it could be hick-uping and throwing things into a unstable state. I can see why it lead you into the direction of bigger injectors, it acts like a lean condition.

Dumb question but is the plug wires and MSD unit far enough away from the ECU and injectors? Just the odd chance that you are hitting a EMI issue and the spark plugs are effecting sensor readings. Other then that I agree a call to Haltech is in order to narrow the field. I am stumped.