Warm idle issue?

[BarnabyHooge]

Both times I've driven my truck over 100 miles, I've had a problem where it kills once I get into traffic.

Example: When I picked the truck up, I drove through the town I purchased it in with no problems. I then drove about 100 miles home, and as soon as I hit city traffic, the thing would cut out soon after coming to a stop. It would start up again right away no problem. If I put it into park right as I stopped, the idle would increase and stay running, but once I dropped it into drive it would kill.

Same thing happened yesterday. I drove a 100 miles round trip. First 20 minutes of city driving were fine. Not too long after I got off the freeway on my way back, the thing just would not stay running at a red light, stop sign, etc. unless I held the brake down with my left foot and lightly feathered the accelorator.

I've been told it may just be a curb idle issue, but I thought I'd get the experts here to weigh in.

The Carb is a Holley 4160 if it matters.

Thanks!