having problem with bucking and surging on 1991 Ford Ranger

bucking surges at a stop. i have replaced mas and computer and truck still bucking and surges. no codes.

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1 answer 1 comment
It could be many things, unfortunately and without experiencing the problem first hand or being able to do some basic diagnostic tests its hard to say. Look for air/vacuum leaks around the intake manifold. Look to see if the EGR valve either leaks or does not seal/fully close. Important to look and see the ignition system isn't causing the misfire/stumble.
if ignition is causeing mis fire would it show a code