1991 F-250. feul injected 460 w/c6 tranny. acts like it is missing when engine runs at 3000rpms. accelerates just fine and runs wonderfully below 2900 rpms. just when i try to plane out around 70 mph the engine starts acting like it is missing a cylinder.it will also act like that in neutral.it starts fine and idles smooth.

i have a 1989 f-250 with a efi 460 with 5spd manual and is doing the same thing, ive checked spark, compression, injectors and all are fine( pulled a 302efi out before the 460) it seems to me like a vaccum- egr valve or fuel/air mixture-O2 sensor, let me know if you find something i have a 1989 f-250 with a efi 460 with 5spd manual and is doing the same thing, ive checked spark, compression, injectors and all are fine( pulled a 302efi out before the 460) it seems to me like a vaccum- egr valve or fuel/air mixture-O2 sensor, let me know if you find something

did you check cap and rotor? that would cuase this and also a weak ignition coil would also cause this as rpms go up bad coil cant keep up with demand did you check cap and rotor? that would cuase this and also a weak ignition coil would also cause this as rpms go up bad coil cant keep up with demand