Wagoneer won't idle

[brentwood]

I have an 82 wagoneer with 258 and motorcraft 2100. It's been running pretty well for about a year now. I drive it once a week. I went out to start it today and heard a pop noise. It started on 2nd try but it cuts off as soon as I let off throttle. I even drove around the street to let it warm up but still shut off when it should idle.
Maybe bad alternator? Or something wrong with carburetor?
Appreciate any help.

[joe]

If it backfired through the carb, a blown power valve would be my first guess.

[brentwood]

OK, is there a problem that would cause the power valve to go bad? Or should I be good just replacing it?

[joe]

The carb backfiring will generally destroy the pv.

[440sixpack]

Sounds like a good guess, but it should be running rich if that's the case. is it?

Could be an ignition problem too.

[PBG928]

Are all your vacuum hoses connected or plugged if applicable? Mine did same thing and once we found two disconnected vacuum hoses and corrected the problem it ran smooth again.

[brentwood]

Sounds like a good guess, but it should be running rich if that's the case. is it?

Could be an ignition problem too.

I don't think it's running rich. Hard to tell though because it shuts off as soon as I let off throttle. Starts right back up. It has started and ran fine for the past year and haven't made any changes recently.

[HikoJeep]

I had same thing happen to me twice now, once two years ago and just last week. Both times I heard a pop, backfire through the carb, then it would not idle at all. Had to keep my foot on the petal in order for it not to die. In my case PO put Holly carb and spacer that he used has a vacuum connection in the back that is not used. I went to auto parts store and got some rubber fitting that are for capping vacuum ports. This time however I put zip tie over it as well just to be little more secure. Hope this helped.
Edit: I forgot to mention that easy way to locate the vacuum leak is to use carb cleaner around vacuum hoses, or carb. Have engine running, spray little around an area and listen engine idle. If it start to idle faster you have located the leak. I did this the first time and worked great.

[will e]

Yeah, it is most likely either a vacuum leak or blow PV.

Do a visual on the vacuum lines. If it doesn't even idle in park have someone keep it running and listen under the hood for a vacuum leak.

[brentwood]

Thanks for all the help. I finally had some free time to work on it today. I replaced the pcv valve, replaced the old pcv to carb vacuum line, and replaced the power valve. It's idling well again! Took my son and dog for a little ride at sunset.
Planning on replacing spark plugs next weekend.