Hey guys, I have a late 04 that has had a stumble after driving on the interstate for quite a while. It was fairly minor and didn't seem to effect performance at all. It 95% of the time went away if i let the truck sit for a bit.
Then around Thanksgiving last year it ran awful when I started it first thing in the morning. So i check my FICM and sure enough my voltages were in the 30's.
I ordered a 58v from Vivian@ Quick Tricks and installed it in December. That fixed the cold start issues, but it still felt like it had a miss when it warmed up on the interstate.
I had hoped it was possibly stiction, so i switched to T6 Rotella and Rev-x. I also changed fuel filters and a new thermostat as i could only get to 176 degrees on the interstate.
It felt like it might have helped the problem but I think it was just me trying to justify putting $250 worth of Oil and filters in my truck.
I had put up with the rough idle for about 2 more months thinking it could be injectors and I decided to take it to a dealer to have a balance test. When i took the truck to the dealer the miss was gone completely and their test was a bust.
So I have been trying to search for people with similar issues as me and i came up with perhaps the ICP sensor. My voltages where swinging from .7 - 1 on my CTS when it would stumble. I replaced the sensor 2 weeks ago and it did not help any.
The miss is getting much worse and is now apparent anytime the truck has reached operating temp.
You may want to check the throttle plate on the intake. The 03 and early 04's had a throttle plate and actuator, mid 04 they did away with the actuator but left the plate in jammed in the wide open position.
On a few trucks I have found this plate to have moved partially closeing off the intake restricting air flow. Some were actually flopping around causeing random rough idle/stumbles etc. In 05 the plate was removed. A possibility, altho rare.
Lord I shall lead them to the water but I will not try to make them drink