Lost of power and weird throttle issue
 

I have a 97 Dodge with 205K on it. Recently, there was a fuel filter leak. (I replaced it 10K ago with a WIX). So I replaced it back with a Mopar fuel filter. First start up, it still leaked so I looked around the housing with an inspection mirror and I couldn't find any cracks. Started up the second time and the leak went away.

But ever since the fuel filter replacement, the truck felt weird. It doesn't have the same amount of power it did before. Before I can acclerate to 2200 rpm and falls flat after that. Now it falls flat after 1800 rpm.

When it's unloaded, during aaccleration, I can feel the resistant in the accl. pedal. There is like a hump in the middle of the pedal travel. But it's not always there. What's weird is that when th hump shows up during driving, and put it in neutral and rev and it would rev fine with a smooth pedal travel. I have never felt the hump when there is a load, either on the truck bed or my car trailer.

I have zero clue where to start. Please point me to some suggestions or what I should test.

Check that the line off the back of AFC housing to the manifold is intact.
If you have the type of wastegate where the line goes from the AFC up over the engine make sure it's also in good shape.
You could also have a ruptured AFC diaphragm.

Thanks infidel. Because of your suggest I found the problem. I feel stupid now too.

After checking the AFC for the wastegate and manifold line and both of them being good, I decided to turn the throttle cable on the injector pump to see how it swing the AFC actuator. Then I saw what I did wrong during my fuel filter replacement .. I didn't tuck the water senor harness on the fuel filter housing away so it got caught on the AFC actuator prevent it from turning at far as it can. That explains why it felt flat quicker (1800 rpm) since I didn't fully accelerated.

Moved it so the AFC actutor can swing fully now and it's back to normal. Took it for a WOT and it revs to 2500 rpm with no problem.