hesitation

Are there any other symptoms, smoke from exhaust, vacuum leaks... Have you checked the catalytic converter for plugging?

Also, do you have a scanner that will provide real time information?

Here are a few guides that will help you figure this out

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

https://www.2carpros.com/articles/engine-hesitates

hello, i have a 2004 mitsubishi eclipse with 66,000 miles on it. The car has never given me any problems,until 6 months ago i noticed it was hesitating at 2000 rpms and my check engine light came on. About 3 months i got a tune up and tightened the aftermarket air intake, and the the hesitation seemed to go away, but it came back last weerk and now it hesitates at about 1500 rpm. I thought it might have been the mass airflow sensor but i am not sure. what do you think.

Scan the computer for codes/- below will cause your problem

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

Good Morning. When starting from as stop, the car will "lag" or hesitate. Extra throttle will smooth out the hesitation. This occurs from 1st gear through 3rd. 4th and 5th do not seem to have an issue. The engine seems to idle fine. When we first noticed the problem it was happening in 1st gear only. The engine stuttered so badly the Check Engine light came on as if the car had stalled but the engine caught back up and stayed running. Not sure where to even begin. Vacuum Leak? Bad plugs? Distributor? MAP Sensor? O2 Sensor? I am lost. Not sure if having a computer diagnostic performed will even yield results. Any assistance is appreciated

1999 Mitsubishi Eclipse Lagging or hesitation

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

Stumbles, hesitates while accellerating, but once you get up your speed, it accellerates good, almost sounds like it is comin through the air intake, just started this all of the sudden, had a timing belt put in a couple months ago, but has ran fine until now,
Thanks,
Racnrog

1997 Mitsubishi Eclipse Engine hesitates while accelerating

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