stumble/pop under load.. hotwire issue

[williamsGN]

Troubleshooting a friends car that idles fine, stumbles and pops even with a slight load, checked the usual culprits.. car only reads 12.3 at the pump harness - 13.7 at the alternator... is this typical or possibly the issue.

 

[GullsGN]

Typical. Maf? Give it a rap while it is still running. If it stumbles replace it. Unplug it. Does it run better. Ignition modual going out?

 

[williamsGN]

Mafless set up, swapped out coil/IM with mine, which works good. Checked voltage on mine @14.5v... even directly at the alternator on his its 13.7, which may be a little low.