I have a 91 F150 4x4 351W automatic,for some time it has been miss firing when I get over 2000 rpm it will buck and jerk while the tach.needle dips I have done a complete tune up checked the sensors and replaced the o2 sensor and fuel filter cleaned the injectors and put in a new ignition switch every thing seems to make it worse. Has anybody else had this problem?
In my 64’ Falcon I had the same problem. Turned out to be a weak coil and burnt points. I don’t know exactly how the ignition system works on a 91 ford, but I would think it is an ignition issue.
Check the distributor.
I put a new coil in it along with cap and rotor.But it runs great until it gets over 2000 rpm