I recently ran a thread about a 95 f-150 5.0 EFI having no power at low rpm's. I had bought this truck about a year ago but probably have driven 4-5k since I've had it. Changed plug wire, plugs, cap, rotor when first got truck and after suggestions about no power, just recently replaced coil (which was big help) and fuel filter. Now it seems to miss badly under load conditions. Moved to mountainess area and climbing hills on interstate at 55mph seems to miss until transmission downshifts out of overdrive or to 2nd gear. Recently had transmission shutter problem fixed with synthetic fluid, shutter stop, and filter change. I can be ideling and turn on AC and feel significant miss. Any ideas???????????? Trans is auto E4OD. Checked timing, Computer code 111, at a loss...............

 

The fact that it behaves differently at altitude is a reson to suspect the MAS (Mass Airflow Sensor) which I just replaced after experiencing somewhat similar problems when driving from sea level to the mountains. (Some trucks have a MAP Manifold Air Pressure sensor instead of MAF)

 

whats the mileage??
maybe dirty injectors

 

I've been reading some other posts on here, especially about the plug wires cross-firing, do you think since I just changed the coil that the now better voltage to the plugs and on the plug wires would cause cross-firing. I had poor power at low rpm's was the reason for the coil change. Now the power seems to be there but along with it came a miss. Miss is very evident when in Drive with ac on. Turn off ac, and you don't notice it, or put in Park with ac on and you don't notice it. Don't know how many miles on rebuilt motor. I think I have vacuum problem also, light throttle driving with ac on diverts air thru ac registers from vents in dash to defrost vents at windshield. Let off accelerator, and air returns to dash vents............