What we need to do here is confirm the fuel pressure is correct when that checks out, check the exhaust system for restriction, throttle position sensor/MAP sensor to include the cam and crank sensors.
Dirty fuel injectors (cleaning the injectors often fixes this).
Bad TPS (throttle position) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)
Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:
Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires
Friday, August 22nd, 2008 AT 4:06 PM