I've had the 351 in my 94 f150 4x4 rebuilt. I did an egr delete when reinstalling. Installed engine and got it running but it has rough idle. Surges and then almost stalls. Checked plugs and they all have black soot so it seems the air/fuel is off. Changed o2 sensor but haven't rechecked plugs to see if that has alleviated the rich condition. Any ideas where to start? I've looked for vacuum leaks and checked or disabled most sensors I can find. This video shows how it's running. https://photos.app.goo.gl/bkP8pc4fysWE8asG8

 

Surging and stalling suggests a problem with the IAC, typical problem with the Gen8s (87-91), but not so much in later years (Gen9 92-96), where the piston would gunk up and stick.

Towards the black soot, thinking by 94, MAF was used (instead of the older MAP) - has the sensor been cleaned lately? Be sure to use the MAF cleaner, carb cleaner will eat it up.

Have you tried pulling the computer codes? Obviously, would expect EGR faults, but has it flagged anything else that may be of help?

Concerned about the EGR delete and the disabling of sensors - the computer is not programmable, so absence of these inputs may freak the controls out a bit.

 

I installed a new MAF sensor and got a code reader but it only showed codes from the egr delete since I had the sensors unplugged. I got and egr delete plug for the intake plenum and simply unplugged the tab and tad sensors which you can get plugs for those too just haven't yet. I agree deleting egr may throw it off but trying to track down exactly what may be causing it.