1998 Mustang GT hesitation in 2nd-3rd gears between 1.5 and 2.5K RPM
One week afte I replaced and recharged my AC comprssor my car would start hesitatting under steady load. THe night it all began my battery would suddendly die. After jumpstarting it the hesitation started and my AC clutch would engage more often than usual.
Things I've already did:
Replaced the air filter
Replaced the MAF sensor
Did a smoke test for possible vacuums leaks. None found
Cleaned the throttle body plates.
Replaced the Idle Air Control Valve
Replaced all spark plugs. Used Motorcraft Platinum gapped at 0.054
Replaced the wires. Used dialectic grease.
Replaced stock coil packs with new Motorcraft ones.
Fuel delivery system:
Replaced the fuel pump
Replaced the fuel filter
Replaced the fuel pressure regulator. Still has 0 PSI with key on, engine off, 29 PSI at idle and vacuum line connected to the pressure regulator. 40 PSI when the vacuum line is disconnected. Clearly, I have low fuel pressure but I don't know what else could be the culprit in the fuel system given the already replaced parts. Relays and fuses? Voltage going tot he pump?
Thought about replacing the injectors but I don't think that would help. Leaking or clogged injectors would cause a more or less constant misfire. I might be wrong.
Replaced both upstream O2 sensors because I had codes for them. (had a lean fuel condiiton on bank 2 and rich condition on bank 1 at the same time. Codes gone after I replaced both O2 sensors.
Replaced the throttle positioning sensor.
Replaced the temperature sensor for the engine.
The misfire started one week after I replaced the AC compressor. Now I am thinking that it might be the crankshaft positioning sensor since it is located next to the AC compressor. I might have damaged it slightly or something. I have no codes whatsoever. It idles well. Runs good in 1st, 4th and 5th gears.