73 F250 stalling

[Kevguero]

Last week when I put gas in my truck, the attendant misunderstood me and put supreme in the tank instead of super. I drove it for a few days with no problem. Last night I drove it about six miles, parked it for a few minutes and then when I started to drive home, it stalled on me when I come to a stop sign or had my foot off the gas. When I let it sit for a couple minutes, it would start up again and be fine for a few blocks, especially if I shifted in to neutral.
Could the supreme gas be the issue? Do I need to adjust the carb to keep it from stalling?
BTW- it's a 390 automatic

 

[SuperCab]

I'd have to guess the premium fuel is just a coincidence... Shouldn't have an effect.

When it does run in its own does it idle normally?

My first thought would be that you've sprung a vacuum leak... Maybe a hose or cap has come off?

 

[Kevguero]

Stalling

Thanks Frank. I went out and started it up a little bit ago. It idled high but it didn't die. I let it run for over five minutes. I did notice a bit of oil leaking on the front of the engine just below and to the left of the right manifold, looked like coming from the seal. I did notice the clip that holds the hose running from oil cap to the air cleaner was missing, but it hadn't come separated. Then I noticed a very small amount of steam coming from hose when I had the air cleaner off. Do I maybe have a blown seal. I also posted a while ago about my oil pressure gauge dropping to low after I had driven it for more than 20 minutes. Related?

 

[SuperCab]

A small amount of smoke or vapor coming from the valve cover while the engine is running isn't unusual... The fact that it idles high still makes me wonder if you have a vacuum leak.