New engine tbi 5.7 1994 gmc.

[Brian Harville]

New engine, new distributor wires plugs, stock setup. New iac, tpms, egr, new vacuum lines also. Base timing at 0°. Rough idle and surging backfire through tbi. I'm at a loss.

 

[scott2093]

I'm at a loss

Well that's a start...
Guessing everything has been checked over a few times?
Pull any codes?
This manual from the sticky is pretty good for symptoms

1994_NATP-9442_DRIVEABILITY_EMISSIONS_ELECTRICAL_DIAGNOSIS_MANUAL

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