1994 Ford E-Series Van stuttering during acceleration

This van has stumped a mechanic with 40 years experience. The engine sputters or falters at various intervals even at an idle or accelerating up hill.

Smog check technician recommended checking engine ground point(s).

This is our last hope. Can you please tell us where they can be found on the van.

If you have any other recommendations please feel free to share them.

Thank you.