Inconsistent Idle

[tmann166]

My bronco is having trouble keep a constant idle speed. I don't have a tach, but can feel the engine revs changing at idle. It also has a slight misfire on one side of the engine, that I can hear through the exhaust. Also if i am running in third gear and gas it to downshift to second, the engine stutters then continues smoothly. I have no idea where to start with this problem. I think the carb might need some adjustment, but I really have no idea. Any help would be great. Thanks guys.

 

[daddyg]

Sounds like the carb may need to be rebuilt. Also check your timing.

 

[BG's 68 Bronco]

Have you had a tune up lately? That's where I'd start if its been awhile.

pcv valve.

 

[tmann166]

The carb is only a year and a little bit old. Its a holley 4bbl. I changed all the spark plugs two weeks ago and the ignition control box is only about 3 months old. I noticed tonight while driving home that there was a high pitched noise, sounded like a vacuum leak. I couldn't locate where it was coming from but I think it was on the left side of the end. Possibly the PCV?
Thanks

 

[Doyle]

Either, a vacuum leak or a stuck PVC, could cause the problems youv'e got.