Misfires when transmission is in first and second gear, also loses power going up a hill

Welcome to 2CarPros.

A few different things can cause this. Components such as a plugged catalytic converter, bad crankshaft position sensor, low fuel pressure, and so on can all have an affect on performance.

Here is what I suggest: Lets start with the basics. Make sure fuel pressure is within the manufacturer's specs.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Here are the manufacturer's specs for pressure:

Fuel Line Pressure .................... 46-51 psi (320-350 kPa)
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Also, a bad crankshaft position sensor can cause a misfire.

https://www.2carpros.com/articles/how-a-crank-shaft-angle-sensor-works

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

https://www.2carpros.com/articles/crankshaft-angle-sensor-replacement

Picture 1 shows the location of the sensor.

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A partially plugged catalytic converter can cause this, too.

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

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

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

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If you have access to a live data scanner, I would like you to check the following:

Fuel Trims both LTFT and STFT

Next, check engine coolant temp sensors reading (ECT). The ECT tells the computer how rich or lean to make the air / fuel mixture. If it is indicating the wrong temp, mixture will be off and cause power and misfire issues. Also, the computer won't know that the sensor is wrong, so no code will be set.

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Let me know if any of this helps, and what you find.

Take care,
Joe

Welcome back:

The only things I can suggest is for him to use a live data scanner to see what is actually happening when the misfire occurs. He may even want to remove an oxygen sensor to see if there is an restriction in the exhaust.

IF he has checked everything, something is causing an intermittent misfire. IT must be brief enough for the computer to not recognize it as a problem.

I wish I could provide a specific issue, but he has checked everything the same as I would have, but I don't know if he drove it with the scanner attached to see what was happening or if he considered a possible restriction in the exhaust (catalytic converter).

Joe