Are you still looking for the Nelson's recipe?
My Mom got this from the original cook before it went "commercial" many years ago. It's what I still use today.
The key is to keep dipping it, because the grills they use commercially actually cycle the meat and potatoes (and now sometimes pork chops) in and out of a huge vat of the liquid.
And yes, I do use the "Accent" (MSG). We make it so rarely that I'm not worried about it.
I've never tried it with potatoes, though.
GOLDEN CHICKEN BBQ SAUCE
1/2 c margarine
1/2 c butter
1 c cider vinegar
1 Tbsp salt
2 Tbsp Worcestershire sauce
1 Tbsp “Accent” flavor enhancer
1/2 tsp pepper
Makes enough for about 3 small chickens. If you boil chicken pieces briefly, the fat is less likely to catch fire on the grill.
Heat margarine and butter in saucepan until melted. Add rest of ingredients and stir well.
The key to flavoring the meat well is to dip the pieces into the sauce as it is grilled, instead of brushing it on. Dip frequently. Do NOT dip when chicken is nearly done because of the raw chicken juices left in the sauce. Make sure it's fully heated/cooked after the last dip, to burn off any leftover raw juices.
*May marinate for a few hours or overnight to enhance taste
*May experiment with ingredients to your tastes, adding liquid hickory smoke, Tabasco sauce, herbs, etc.