So, I've had my '01 excursion 2 months now. I've put about 1200 trouble free miles on it, until the past couple week when it started acting funky. I first noticed it when i was cruising on the freeway, about 65-68 is where i generally set the cruise. Suddenly, it felt like my speed was ever so slightly, and the engine noise changed like the rev's were jumping but there was no noticeable change on the tach. It went away after a few minutes.
2-3 Days ago, I was driving around, and the truck started running pretty rough, like it had a misfire. It went away after driving a couple city miles (a few stop lights, slow driving under 35mph.).
Yesterday, I took it on a 25 mile drive, and the same thing as above, but for the majority of the drive on the freeway, it was sluggish, the cabin was vibrating, and power, especially uphill, was non-existent.
I parked the truck, and started looking on here, sounded like it could be IDM or UVCH.
I attemped to remove the driver's side UVCH outer plug while running. The truck actually started great this morning. When i pulled the driver's side plug,rpms dropped and got real lumpy. As soon as i put the plug back in, it ran rough, just like the symptoms above. I turned the truck off, while i could figure out how to unplug the passenger side without removing anything. But as soon, as i turned the truck back on, it ran like crap. RPMS jumping, blowing smoke, and i turned it right off. I made sure the driver's side UVCH plug was tight/secure, and that nothing else had come loose. I started the truck, and same thing (this time i had the camera handy).
Help!! I should also mention that have been check engine lights since any of this began.