My 97 F-150 4.6 has bad pre ignition problem on the highway when stepping on throttle but no codes show up and engine light is not on I’ve replaced the EGR valve and tube to no avail any suggestions from anyone on this matter I’m told if the knock sensor or any other sensor is bad it should turn on my engine light.

 

Yes the light will come on if it was a sensor your knock sensor wouldn’t be doing that the only thing that does is keep the engine from knocking if the wrong type of gas is used. It is loosing power sounds to me like from what you describe check Your idle air control valve occasionally it does get dirty and makes a vehicle do just what you described and you can just get some cleaner and clean it just don’t spray like carburetor cleaner or brake cleaner in it that will damage it get the cleaner made for that part.

 

I would be checking the operation of the EGR valve. Disconnect the vacuum line off the valve while the engine is idling, apply vacuum to the valve. The engine should stumble bad if not stall completely if it is working downstream from the valve. A blocked passage will allow the engine to continue running. If that checks out, determine if you are getting vacuum to the valve. You shouldn't have vacuum at idle but if you raise the engine speed, vacuum should be present to open the valve.