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sprinkles08, ASE Certified Technician
Category: Car
Satisfied Customers: 22675
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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Mitsubishi Eclipse GS: 03 eclipse, 4 cy

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03 eclipse, 4 cylinder, everything stock. The problem I am having is loss of power in all gears when gas pedal is pressed hard and medium. When gas pedal is pressed lightly, acceleration and power is good

Hello and welcome to JustAnswer!

Have you checked for fault codes? The first thing you'll want to do is check for fault codes and see if there are any stored that are related to this problem. If you don't have a code reader or scan tool of your own you can have the codes read for free at most large parts stores. There may be something set that will be needed for use as a starting point for diagnosis.

There are a few things most suspect that should be looked into if there are no codes stored.

Fuel demand is much greater under higher engine loads and low fuel pressure will cause your symptoms. Doing a fuel pressure test while under a load may show that pressure is low and causing the problem.

It could be the MAP sensor. The MAP sensor tells the ECM how much vacuum is in the intake and it's signal is used to calculate engine load, injection and ignition timing and injector quantity. An incorrect MAP sensor signal will cause your symptoms.

The mass airflow sensor reads the amount of air coming into the engine. If the sensor was failed or even just dirty enough it could cause this. Cleaning the sensor with some mass airflow sensor cleaner and seeing if that helps would be a good idea.
Customer: replied 4 years ago.

somehow I was able to fix the problem. I put the car into Park and then rev'ed the engine several times. I saw the RPM's stall and drop a few times and then kick back up. To verify everything was normal, I drove around the block and everything was fine.

What you noticed was the rev limiter, the ECM limits RPM in park and neutral to protect the engine from damage.

It sounds like the problem is intermittent which can make it a little trickier to diagnose.
Customer: replied 4 years ago.

the stalling also happened when I was driving. I could be at 20, 30, 50, or 65 mph and soon as I hit the gas pedal medium or hard, it was like the engine didn't recognize I was hitting the gas. There was no jerking or weird noises.

A lack of power or hesitation can be caused by many things, many of which I described earlier. The first thing I would recommend is seeing if any fault codes are stored and go from there. There's a good chance that a code has set that will aid in diagnosis.
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