Rough idle only in gear


Asked by Apr 20, 2016 at 12:57 AM about the 1978 Ford F-150

Question type: Maintenance & Repair

Warming up idles rough then sometimes it will run great
but then most of the time when I stop at a stop light driving
through town it will just sputter rough idle and almost die
sometimes I have thought maybe a messed up Valley got
new plugs in it any thoughts

3 Answers


Could be time for a carb rebuild, was it updated to run this trash they call fuel today? If not that might be your problem and you should also replace all the rubber fuel lines with the new multi fuel hoses. This is assuming that you have checked for vacuum leaks at all the hoses and intake.


It has a rebuilt motor and a new carb on it but Ithe should be capable of running regular fuel it's only a 78


Ok then apparently it hasn't been set up properly, you will have to adjust the air mixture screws in the carb base. You may want to check out you tube for a video on how to do this if you haven't set one up before, it's fairly easy once you learn how.

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