2000 Toyota Corona

Engine Performance problem
2000 Toyota Corona 4 cyl Two Wheel Drive Manual 109200 miles

Car with 4A-FE engine is not accelerating smoothly. Local mechanics r saying problem with vacuum on the top right corner of the engine. Hat should I do?
July 24, 2009.

Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) 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

Jul 24, 2009.