Rumble at idle, lack of power, hesitation

Hello, I have a 3rd gen with the 2.7.

About a year and a half ago I had an animal chew up a very expensive harness. I'm not knowledgeable enough to say which harness exactly, but, the harness was replaced. However, it hasn't ran the same since.

At idle the engine will occasionally drop to 600 rpm or so and when it does a slight engine rumble is present. I've heard of a lot of these engines doing this and a number of causes, but since it didn't do it before, I think it might be related to the other issues.

There seems to be a lack of power and I have to press down extra hard on the accelerator to get it to move/ down shift. There is also a bit of hesitation, although some hesitation was present when I bought the vehicle new. Just seems like the transmission doesn't want to downshift sometimes.

I replaced the plugs with OEM parts about 10k ago. The throttle body is very clean and the air filter is very clean. I have done a fuel system flush at Valvoline and ran techron fuel injector cleaner through it.

I'm just hoping maybe it's something I can fix before spending a fortune at a shop or dealership.

 

I'm not able to help you but would like to let you know what others may be asking from you to help you. A picture of the service order for the repair, I presume it was done by the dealer, and the type/part number of the harness should be there.

There is not a lot of 2.7L experience here on TW.

 

How many miles on the truck?

 

78,349

 

I just replaced my serpentine belt for the second time ( I’m at 188k) and notice the throttle tip in is back and there is no lag. Light throttle feels tight. I dunno, maybe a new belt will help. Good luck!