Kind of hard to visualize the items you are talking about. The vacuum line that goes in side the car is to drive your air doors for your defrost, and vents. This vacuum line should go from the intake to a vacuum tank. In that line should be a check valve. Then from the tank to thie inside of the vehicle. The check valve is to keep a vacuum leak inside the truck from causing driving problems. When you described before the vents changing when you went up a hill, makes me think that maybe that check valve has gone bad, and maybe you have a vacuum leak.
The cables that go to your throttle body should only be two. A crusie conrtol servo cable, and a throttle cable. The down shifting is all done by computers.
I would make sure that vacuum system going to your inside is in good shape, and I might even disconnect it a plug the hose to eliminate that as a problem. Then see if your truck runs good. If it does, then find the problme in that vacuum system. If it doesnt make a difference, then place a vacuum gauge on that line and see how you vacuum is. It should be around 18-19 inches and steady at idle. If you have a large leak, then it should run rough.
Monday, August 14th, 2006 AT 8:40 PM