Misfiring at 2,500 RPM's, worse when driving up a hill

Hello, I'm Danny.

Is the check engine light on? If so that means a diagnostic code is stored in the cars computer. Here is a tutorial showing what is involved for checking codes:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

If you don't have access to a code reader or scanner most auto parts stores have a tool loaner program and can rent you one. Auto parts store like AutoZone can check codes for free. I also believe you could possibly have problems with a plugged or failing catalytic converter. Here are a few tutorials on catalytic converter symptoms and replacement for you to view:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

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

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

Get back to us with any code information or tests you performed and we'll go from there to help with diagnosis. Hope this helps and thanks for using 2CarPros.

Hello again.

Okay, since you mentioned that you changed the spark plugs and that has taken care of the misfire then I would suspect you might have a plugged or defective catalytic converter as I stated in the last post. If you have access to an infrared gun the best way to test for blockage or deficiency is to measure the heat at the inlet and outlet. The outlet temperature will always be hotter than the inlet in a properly working catalytic converter due to the catalyst process. If the converter is bad due to blockage or failure then the outlet temperature will be lower than the inlet. If you don't have access to an infrared heat gun most auto parts stores have a tool loaner program and can rent you one. You can also buy relatively cheap at a hardware store or home improvement stores. Let us know what you find out and we'll go from there after testing. I've attached pictures below of its location and removal for you. Hope this helps and thanks again for using 2CarPros.

Danny-

Thanks for the additional info. This would actually support what Danny is suggesting that you could have a plugged exhaust. What appears to be happening is when the RPM is raised, it is not able to move enough air through the exhaust due to the restriction. Then the restriction is causing a misfire and the raw fuel is going through into the converter where it is burning in the converter causing the higher outlet temp. I would suggest removing the up and down stream o2 sensors and drive the vehicle. It is going to be loud but should not misfire any more. If it does not at 2,500 RPM's then you need to replace the converters.

https://www.2carpros.com/articles/exhaust-system-removal

Also, here is the process below of the converter from the manual. Let us know what you find. Thanks

Hello again.

Just checking in to see if you were able to test and see if you have excessive back pressure in the exhaust system-muffler from our last post causing this drivability issue. Thanks again for using 2CarPros and keep us updated or let us know if you have any further questions. Happy Holidays.

Danny-

Have you monitored fuel trims to confirm this is rich? I don't think it is necessary as it is a safe assumption but I don't like to make assumptions because if we are wrong every thing from that point is wrong.

However, if we have a rich exhaust then that means the issue you are having is a misfire that is not burning all the fuel. So that raw fuel is going into the exhaust and it is burning in the converter which is why the temp is higher coming out.

So if it is not clogged then we have to go back to the engine and cover the basics. Pull the plugs and get a picture of them so we can see if they are fouled. If they are they need to be replaced. I attached below a chart showing spark plugs that are worn. That will give us more info as to what the issue is.

Then we may need to replace or at least try and clean the injectors because they may be sticking and dumping too much fuel.

Let us know what the plugs look like and we can go from there. Thanks

Hello again.

I'm leading to believe the injectors might be sticking allowing more gas than usual to enter the cylinders and causing a rich condition resulting in misfires. This might be caused also as you stated by the truck sitting for 2 years and having them being gummed up from sitting with old gas. There is a Seafoam brand treatment you might want to try using to help free up the injectors. You just add to the gas tank. I was able to start a car after sitting 5 years with old gas in the tank and wouldn't start by using this. I've attached a picture below of what Seafoam brand looks like. It is available at auto parts stores. Hope this helps and thanks again for using 2CarPros.

Danny-