Okay I've been having a problem and it been going on for a little while now when driving out on the free lanes you got your slight hills well it shifts fine mostly up to about 55mph when going up a slight hill or flat ground and I give it throttle the rpm's run up to about 3000 and over but never to the 4000 point as if it don't have the power acting like it's dragging but still holding speed with rpm's at 3000 as soon as I start to go down the hill and gain speed it shifts not too sure what the problem is I've had transmission worked on the computer is from a 97 360 half ton spark plugs changed needing some help here any ideas on what the cause could be I've also had the wiring harness replaced .

 

Possible plenum issues, leading to a clogged cat. That's make the truck feel seriously down on power. You can check it by just looking down the throttle body, see if you see any oil pooling. A more thorough check is to pull the throttle body, and look at the back of intake (inside), and see what ya see. It's a common problem on these trucks.

So, once you are sure the engine is running right, see if the problem persists, and we can go from there.

Welcome to DF!

 

Yep, your cat has a hairball.

Hey You must have been busy, otherwise he would have mentioned to remove the front O2 sensor from the pipe (it will throw a code). Leave the hole open,motive it around and see if it doesn't feel better. If it does, you cat is clogged (probably from your blown plenum).

 

I was just wondering when the last time if ever, have you done preventative maintenance or scheduled maintenance to the transmission and do you have a external transmission cooler. Also did you say grind on the throttle body? The tolerances between the body and butterfly valve can greatly affect the idle and performance of the vehicle.

 

Three. Year. Old. Thread.