been awhile since I posted. I'm having a lose of power up hill. When you get up around 2500rpms you can hear a tapping sound. But not at idle or lower rpms. So here is what I've done so far. Hughes plenum kit, cap button, plugs, wires, tps, iac, air filter, pic valve from dealer, cleaned the throttle body,

the only codes I have are for evap purge Sensor

the only things I could think of are fuel pump or fuel injectors. But on my 97 there is no check valve to test pressure.

If if there is anything anyone can think of that I might be missing I would appreciate any help.

Is is it possible that the tapping I hear at 2500rpms and above could be a leaking exhaust manifold.

 

O2 sensors? Clogged cat?

What you are hearing is likely spark knock. Try removing the front O2 sensor from the exhaust, see if the truck drives better.

 

Forgot I put new cat on right before I did the plenum fix. And if it is in fact spark knock what is the fix for that.

 

Seafoam down the intake. (carefully. I think there is a diy for this.....) Need to clean the combustion chambers. Also need to verify you don't have any other vacuum leaks.

 

Doesn't the vapor canister purge valve (solenoid) create a large vacuum leak when it sticks open?

 

Im not sure exactly how that works. If someone could educate me I would appreciate the knowledge.

 

Mopar has a version that comes out as foam that is much easier to use